“So the Universe is not quite as you thought it was. You’d better rearrange your beliefs, then. Because you certainly can’t rearrange the Universe.” –Nightfall by Isaac Asimov
In three previous posts, we explored the many judgments of Revelation – how they are impacting us today and what they mean for our future. We reviewed the symbolism involved with these judgments and how I believe they should be interpreted.
As I stated in the previous posts – I believe that the Lord’s judgments are present in the world today – they are not going to somehow impact the world only during a future 7 year tribulation period. I believe that we can look at the world today and recognize God’s judgments – and get a good idea how they will progress as we near the time of the bowl judgments.
We should not be looking for some type of obvious ‘supernatural’ event (like water actually turning into blood or the light from the Sun being supernaturally dimmed) – we should look at what is happening in the world and comparing it to God’s Word. As I’ve stated many times, worldly people will always have a ‘logical’ explanation for events happening in the world – they simply will not admit that there is a holy God overseeing and impacting our world.
Hopefully, you now know better.
I’m writing a fourth post on this subject because there are a couple of judgments that I need to clarify – judgments that I could not understand – until now.
In multiple verses we are told about a ‘great earthquake’ and huge ‘hailstones’ that impact the earth near the end of this age. Again – I don’t believe that ‘hailstones’ are simply going to appear one day or that the earth is simply going to experience some type of ‘supernatural’ earthquake – with neither judgment having a worldly explanation.
My thought process has always been – even though God is the ultimate cause of these judgments - what is going to happen in our world/universe to cause these events? What will be the worldly reason for these events?
Until now – I had absolutely no clue.
Before we look at what I believe is a very good possibility to explain these future judgments – let’s review the verses in the Bible describing these events.
“The seventh angel poured out his bowl into the air, and out of the temple came a loud voice from the throne, saying, “It is done!” Then there came flashes of lightning, rumblings, peals of thunder and a severe earthquake. No earthquake like it has ever occurred since mankind has been on earth, so tremendous was the quake. The great city split into three parts, and the cities of the nations collapsed. God remembered Babylon
“‘This is what the Sovereign LORD says: You are the one I spoke of in former days by my servants the prophets of Israel land of Israel land of Israel
“At that very hour there was a severe earthquake and a tenth of the city collapsed. Seven thousand people were killed in the earthquake, and the survivors were terrified and gave glory to the God of heaven.” (Revelation 11:13, emphasis added)
“Then God’s temple in heaven was opened, and within his temple was seen the ark of his covenant. And there came flashes of lightning, rumblings, peals of thunder, an earthquake and a severe hailstorm.” (Revelation 11:19, emphasis added)
So – we see mention of a great earthquake and mention of hailstones/hailstorms in multiple verses. These judgments cause cities to collapse, mountains to crumble and every mountain and island will be ‘removed from its place’. The people on earth during this time are terrified. Serious business – the whole earth is being affected in a major way.
When thinking about these judgments – the first thought that comes to mind is – what in the world could cause something of this magnitude? The answer is – the cause won’t come from this world.
There’s no need to explain the mention of a great earthquake – the description is crystal clear. This earthquake is so great – it affects the entire earth – causing mountains to crumble, islands to disappear under the sea and destroys much of the world’s cities. Complete devastation.
While we are given a clear description of this great earthquake and the devastation it causes – I don’t see any clues that could tell us what would cause it from the world’s perspective.
I believe the key to unlocking this earthquake/hailstone mystery lies with the description of the hailstones and the impact they have on the earth. Let’s look closely at the description of the hailstones and see if we can solve this mystery.
The first thing that should get our attention is that these hailstones cause everyone to hide in caves. Basically, the surface of the earth is being assaulted – and the only way for people to escape – is to go underground. What could cause the world’s people to seek safety underground? Whatever it is – it’s not a one time event – there are numerous hailstones impacting the earth over a period of time.
Are these actual hailstones? No. This is happening worldwide – these hailstones are impacting the world – not an isolated area. The Lord is using the word ‘hailstone’ to tell us that these objects are falling from the sky like hailstones – but they are not actual hailstones.
We are given clues to solve the mystery:
- They weigh approximately 100 lbs (Revelation 16:21)
- These hailstones are described in connection with ‘burning sulfur’. We can reasonably assume that fire is associated with them. (Ezekiel 38:22)
- And the final piece of the puzzle – we are told that ‘the stars in the sky fell to earth’
These hailstones do not originate in our atmosphere – they originate from space. What is described here are objects from space impacting the earth – multiple times.
At this point, if this was all we knew – then we could say that this judgment will result when comets, meteors or asteroids – hit the earth at some point in the future.
However, if we review some information recently proposed by the scientific community – I believe we have a very good explanation for what is going to cause these events to happen. In another year or two – we may even be able to get a general idea of the timeframe these hailstones may hit us.
A couple of weeks ago I came across an article on CNN.com that described a theory by two scientists who have proposed that the Sun may have a companion star. I know what you’re thinking – how is this possible? We’ve always been told that our solar system only has one star – surrounded by planets.
What if we’ve missed something?
As our knowledge of the solar system has increased in recent years – we have discovered other large dwarf planets beyond Pluto.
One such dwarf planet (Sedna) lies billions of miles past Pluto and has an orbital path that takes it approximately 12,000 years to orbit the sun. There’s just one problem – based on our current knowledge of the solar system – Sedna’s orbit cannot be explained.
"Sedna shouldn't be there," said Brown. "There's no way to put Sedna where it is. It never comes close enough to be affected by the Sun, but it never goes far enough away from the Sun to be affected by other stars." Perhaps a massive unseen object is responsible for Sedna's mystifying orbit, its gravitational influence keeping Sedna fixed in that far-distant portion of space? -Leslie Mullen, Astrobiology Magazine
The article had links to other articles – and I eventually discovered that this theory that the sun may have an undetected companion star – was first proposed by Dr. Richard Muller in a paper in 1984 and later published in a book entitled ‘Nemesis’.
You may be wondering what could cause scientists to look for a companion star when it appears that none exists.
Good question – and believe it or not - the answer lies with the extinction of the dinosaurs.
Would you believe that there appears to be evidence that life on earth is devastated approximately every 26 million years (see articles at end of this post)? It’s one thing to believe that a random meteorite or asteroid hit the earth – killing the dinosaurs. It’s something else entirely – if the earth appears to get hit periodically every 26 million years.
If the earth is getting hit periodically - what could cause this?
We have always assumed that we completely understood our solar system – it now appears that we may be missing something – something very important.
The only thing that could explain the earth being hit periodically – would be something in space that we have not seen – something that has a very large mass and has a very large orbital path – something that periodically causes comets from the outer solar system to be hurled into the inner solar system.
NASA is currently searching for this companion star – with the first report due in the next few months. Will we find something? Time will tell.
If we do find a brown or red dwarf star in an orbit around the sun – the first order of business will be calculating its orbit. Once the orbit is calculated – we’ll know if we should be concerned about its potential impact on the earth. If the star exists – and we can calculate its orbit – I’m willing to bet that there are going to be some very concerned scientists.
I recommend that you read the articles below and then re-read the judgments above. Could a companion star cause comets to hit the earth? Yes. Could the gravitational pull from this star cause massive earthquakes on earth as it approaches us? Are the recent major earthquakes around the globe caused by an unseen gravitational force? It’s certainly possible – we won’t know until we find something.
With this additional information – let’s take another look at the first four trumpet judgments:
The second angel sounded his trumpet, and something like a huge mountain, all ablaze, was thrown into the sea. A third of the sea turned into blood, a third of the living creatures in the sea died, and a third of the ships were destroyed.
The third angel sounded his trumpet, and a great star, blazing like a torch, fell from the sky on a third of the rivers and on the springs of water— the name of the star is Wormwood. A third of the waters turned bitter, and many people died from the waters that had become bitter.
The fourth angel sounded his trumpet, and a third of the sun was struck, a third of the moon, and a third of the stars, so that a third of them turned dark. A third of the day was without light, and also a third of the night.” –Revelation 8:7-12)
When I first began to study these trumpet judgments, I focused on the results of these judgments and compared them to what is happening on earth. Looking at the world today, it’s easy to see that human population growth coupled with climate change is destroying vegetation around the globe, our seas are under great stress due to numerous factors and the availability of fresh water has become a serious issue. I simply couldn’t understand how we could be hit by numerous comets/asteroids over a relatively short amount of time. It’s becoming clear to me now.
Although I still believe that these judgments are describing all of the things happening in the world today, when we view these verses with the other verses regarding ‘stars’ falling from the sky – I believe we are reading about how these judgments end. These verses are telling us that – eventually – some comets/meteors/asteroids hit land – affecting the earth’s vegetation – and some hit the oceans – killing sea animals and destroying ships on the seas.
I now believe that it will be comets hitting the earth that darken our skies. Other factors certainly may contribute to the dirt/dust in our atmosphere – but it will most likely be comet/meteor impacts that cause our skies to darken.
Let’s review Revelation chapter 9, verses 1-2:
“The fifth angel sounded his trumpet, and I saw a star that had fallen from the sky to the earth. The star was given the key to the shaft of the Abyss. When he opened the Abyss, smoke rose from it like the smoke from a gigantic furnace. The sun and sky were darkened by the smoke from the Abyss.” (Revelation 9:1-2)
Once again we see that a ‘star’ has fallen from the sky and it is this ‘star’ that causes smoke to darken our skies.
We have previously reviewed what the Lord had to say about the end of this age when we studied Matthew chapter 24. I think it’s important that we understand what is meant when Jesus mentions ‘birth pains’.
“Nation will rise against nation, and kingdom against kingdom. There will be famines and earthquakes in various places. All these are the beginning of birth pains.” – Matthew 24:7-8
What happens during labor? As labor progresses – contractions happen more frequently and are more intense. This is what we’re going to witness on earth. We should expect to experience more frequent earthquakes with greater intensity as this age progresses.
The culmination of all of this is one massive earthquake that impacts the entire earth.
I know that if you are looking at all of this from a worldly perspective – it’s not good news. The problem is that you are on the outside looking in. It’s time for you to know your Creator. He will replace your fear with courage and hope. He – and He alone – can turn you into the person He created you to be.
The true Christian does not place his faith and hope in this fallen world – we can see past all of this.
The end of this world is the result of our fateful decision to disregard God’s guidance and listen to God’s adversary – and we have continued this disobedience throughout human history. The future I am describing here is the inevitable result of our disobedience. We have chosen unwisely – and the results of our poor choices will be catastrophic.
Although our future will be extremely difficult – as Christians we know that we have been promised something greater. This is where we set our sights – on the Lord’s kingdom. We have overcome this world and endure it for Him - and we look forward to the time when the Lord will fulfill his promise to us.
Will bad things happen to this world? Yes. Does our focus change when bad things happen? No.
We are not moved by this world and its ruler.
This fallen world will end and we will then receive our inheritance.
The old order of things will pass away – and He will make all things new.
This story will end – and a new one will begin.
“Do not let your hearts be troubled. You believe in God; believe also in me. My Father’s house has many rooms; if that were not so, would I have told you that I am going there to prepare a place for you? And if I go and prepare a place for you, I will come back and take you to be with me that you also may be where I am. You know the way to the place where I am going.” – John 14:1-4
Then I saw “a new heaven and a new earth,” for the first heaven and the first earth had passed away, and there was no longer any sea. I saw the Holy City, the new Jerusalem, coming down out of heaven from God, prepared as a bride beautifully dressed for her husband. And I heard a loud voice from the throne saying, “Look! God’s dwelling place is now among the people, and he will dwell with them. They will be his people, and God himself will be with them and be their God. ‘He will wipe every tear from their eyes. There will be no more death or mourning or crying or pain, for the old order of things has passed away.”
He who was seated on the throne said, “I am making everything new!” Then he said, “Write this down, for these words are trustworthy and true.”
He said to me: “It is done. I am the Alpha and the Omega, the Beginning and the End. To the thirsty I will give water without cost from the spring of the water of life. Those who are victorious will inherit all this, and I will be their God and they will be my children. But the cowardly, the unbelieving, the vile, the murderers, the sexually immoral, those who practice magic arts, the idolaters and all liars—they will be consigned to the fiery lake of burning sulfur. This is the second death.” – Revelation 21:1-8
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Isaac Asimov wrote numerous science fiction novels before he died in 1992. One of his most famous novels was ‘Nightfall’. The novel describes a world with six suns that keeps the planet in continuous sunlight – the inhabitants of this planet never experience the darkness of night. Eventually, an astronomer discovers that there is an unknown planet orbiting them – that periodically causes a total eclipse. What happens to people accustomed to perpetual daylight - when they are plunged into complete darkness?
I believe that at some point in the future – we are going to experience the same scenario.
Meteor Explodes Over Russia
Space probes feel cosmic tug of bizarre forces
NASA Baffled by Unexplained Force Acting on Space Probes
Meteor Explodes Over Russia
Space probes feel cosmic tug of bizarre forces
NASA Baffled by Unexplained Force Acting on Space Probes
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Some scientists think a brown dwarf or gas giant bigger than Jupiter could be at the outer reaches of the solar system. In this image showing relative size, the white object at the upper left edge represents the sun.
February 15th, 2011
09:03 AM ET
You know how you sometimes can sense that something is present even though you can't see it? Well, astronomers are getting that feeling about a giant, hidden object in space.
And when we say giant, we mean GIANT.
Evidence is mounting that either a brown dwarf star or a gas giant planet islurking at the outermost reaches of our solar system, far beyond Pluto. The theoretical object, dubbed Tyche, is estimated to be four times the size of Jupiter and 15,000 times farther from the sun than Earth, according to a story in the British paper The Independent.
Astrophysicists John Matese and Daniel Whitmire from the University of Louisiana at Lafayette think data from NASA's infrared space telescope WISE will confirm Tyche's existence and location within two years.
The presence of such a massive object in the solar system's far-flung Oort Cloud could explain a barrage of comets from an unexpected direction, according to a December article at Space.com.
Its 27 million-year orbit could also explain a pattern of mass extinctions on Earth, scientists say.
Brown dwarfs are cold "failed" stars; their dimness and lack of heat radiation can make them hard to detect. Gas giants are huge planets – like Saturn, Jupiter and Neptune – that are made up of gases and may lack a solid surface like Earth's.
Whitmire told The Independent that Tyche will probably be composed of hydrogen and helium and have colorful spots, bands and clouds like Jupiter.
"You'd also expect it to have moons," he said. "All the outer planets have them."
Tyche was first hypothesized in 1984 as Nemesis, a dark companion star to the sun. It's been the subject of astronomical research and debate ever since. In July, another Space.com article said the celestial evidence suggests Tyche could not possibly exist.
To distinguish it from the Nemesis star theory, Matese and Whitmire are calling their object Tyche, after the good sister of the goddess Nemesis in Greek mythology.
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Sun's Nemesis Pelted Earth with Comets, Study Suggests
Date: 11 March 2010 Time: 08:16 AM ET
NASA's Wide-field Infrared Survey Explorer, or WISE, will uncover many "failed" stars, or brown dwarfs, in infrared light. This diagram shows a brown dwarf in relation to Earth, Jupiter, a low-mass star and the sun.
CREDIT: NASA |
A dark object may be lurking near our solar system, occasionally kicking comets in our direction?
Nicknamed "Nemesis" or "The Death Star," this undetected object could be a red or brown dwarf star, or an even darker presence several times the mass of Jupiter.
Why do scientists think something could be hidden beyond the edge of our solar system? Originally, Nemesis was suggested as a way to explain a cycle of mass extinctions on Earth.
The paleontologists David Raup and Jack Sepkoski claim that, over the last 250 million years, life on Earth has faced extinction in a 26-million-year cycle. Astronomers proposed comet impacts as a possible cause for these catastrophes.
Our solar system is surrounded by a vast collection of icy bodies called the Oort Cloud.?If our Sun were part of a binary system in which two gravitationally-bound stars orbit a common center of mass, this interaction could disturb the Oort Cloud on a periodic basis, sending comets whizzing towards us.
An asteroid impact is famously responsible for the extinction of the dinosaurs 65 million years ago, but large comet impacts may be equally deadly. A comet may have been the cause of the Tunguska event in Russia in 1908. That explosion had about a thousand times the power of the atomic bomb dropped on Hiroshima, and it flattened an estimated 80 million trees over an 830 square mile area.
While there's little doubt about the destructive power of cosmic impacts, there is no evidence that comets have periodically caused mass extinctions on our planet. The theory of periodic extinctions itself is still debated, with many insisting that more proof is needed. Even if the scientific consensus is that extinction events don't occur in a predictable cycle, there are now other reasons to suspect a dark companion to the Sun.
The Footprint of Nemesis
A recently-discovered dwarf planet, named Sedna, has an extra-long and usual elliptical orbit around the Sun. Sedna is one of the most distant objects yet observed, with an orbit ranging between 76 and 975 AU (where 1 AU is the distance between the Earth and the Sun). Sedna's orbit is estimated to last between 10.5 to 12 thousand years. Sedna's discoverer, Mike Brown of Caltech, noted in a Discover magazine article that Sedna's location doesn't make sense.
"Sedna shouldn't be there," said Brown. "There's no way to put Sedna where it is. It never comes close enough to be affected by the Sun, but it never goes far enough away from the Sun to be affected by other stars."?
Perhaps a massive unseen object is responsible for Sedna's mystifying orbit, its gravitational influence keeping Sedna fixed in that far-distant portion of space.
"My surveys have always looked for objects closer and thus moving faster," Brown said to Astrobiology Magazine. "I would have easily overlooked something so distant and slow moving as Nemesis."
John Matese, Emeritus Professor of Physics at the University of Louisiana at Lafayette, suspects Nemesis exists for another reason. The comets in the inner solar system seem to mostly come from the same region of the Oort Cloud, and Matese thinks the gravitational influence of a solar companion is disrupting that part of the cloud, scattering comets in its wake. His calculations suggest Nemesis is between 3 to 5 times the mass of Jupiter, rather than the 13 Jupiter masses or greater that some scientists think is a necessary quality of a brown dwarf. Even at this smaller mass, however, many astronomers would still classify it as a low mass star rather than a planet, since the circumstances of birth for stars and planets differ.
The Oort Cloud is thought to extend about 1 light year from the Sun. Matese estimates Nemesis is 25,000 AU away (or about one-third of a light year). The next-closest known star to the Sun is Proxima Centauri, located 4.2 light years away.
Richard Muller of the University of California Berkeley first suggested the Nemesis theory, and even wrote a popular science book on the topic. In his view, Nemesis is a red dwarf star 1.5 light years away. Many scientists counter that such a wide orbit is inherently unstable and could not have lasted long — certainly not long enough to have caused the extinctions seen in Earth's fossil record. But Muller says this instability has resulted in an orbit that has changed greatly over billions of years, and in the next billion years Nemesis will be thrown free of the solar system.
Binary star systems are common in the galaxy. It is estimated that one-third of the stars in the Milky Way are either binary or part of a multiple-star system.
Red dwarfs are also common — in fact, astronomers say they are the most common type of star in the galaxy. Brown dwarfs are also thought to be common, but there are only a few hundred known at this time because they are so difficult to see. Red and brown dwarfs are smaller and cooler than our Sun, and do not shine brightly. If red dwarfs can be compared to the red embers of a dying fire, then brown dwarfs would be the smoldering ash. Because they are so dim, it is plausible that the Sun could have a secret companion even though we've searched the sky for many years with a variety of instruments.
NASA's newest telescope, the Wide-field Infrared Survey Explorer (WISE), may be able to answer the question about Nemesis once and for all.
Finding Dwarfs in the Dark
WISE looks at our universe in the infrared part of the spectrum. Like the Spitzer Space telescope, WISE is hunting for heat. The difference is that WISE has a much wider field of view, and so is able to scan a greater portion of the sky for distant objects.
WISE began scanning the sky on January 14, and NASA recently released the mission's first images. The mission will map the entire sky until October, when the spacecraft's coolant runs out.
Part of the WISE mission is to search for brown dwarfs, and NASA expects it could find one thousand of the dim stellar objects within 25 light years of our solar system.
Davy Kirkpatrick at NASA's Infrared Processing and Analysis Center at Caltech found nothing when he searched for Nemesis using data from the Two Micron All Sky Survey (2MASS). Now Kirkpatrick is part of the WISE science team, ready to search again for any signs of a companion to our Sun.
Kirkpatrick doesn't think Nemesis will be the red dwarf star with an enormous orbit described by Muller. In his view, Matese's description of Nemesis as a low mass object closer to home is more plausible.
"I think the possibility that the Sun could harbor a companion of another sort is not a crazy idea," said Kirkpatrick. "There might be a distant object in a more stable, more circular orbit that has gone unnoticed so far."
Ned Wright, professor of astronomy and physics at UCLA and the principle investigator for the WISE mission said that WISE will easily see an object with a mass a few times that of Jupiter and located 25,000 AU away, as suggested by Matese.
"This is because Jupiter is self-luminous like a brown dwarf," said Wright. "But for planets less massive than Jupiter in the far outer solar system, WISE will be less sensitive."
Neither Kirkpatrick nor Wright think Nemesis is disrupting the Oort cloud and sending comets towards Earth, however. Because they envision a more benign orbit, they prefer the name "Tyche" (the good sister).
Regardless of what they expect to find, the WISE search won't focus on one particular region of the sky.
"The great thing about WISE, as was also true of 2MASS, is that it's an all-sky survey," said Kirkpatrick. "There will be some regions such as the Galactic Plane where the observations are less sensitive or fields more crowded, but we'll search those areas too. So we're not preferentially targeting certain directions."
We may not have an answer to the Nemesis question until mid-2013. WISE needs to scan the sky twice in order to generate the time-lapsed images astronomers use to detect objects in the outer solar system. The change in location of an object between the time of the first scan and the second tells astronomers about the object's location and orbit.
"I don't suspect we'll have completed the search for candidate objects until mid-2012, and then we may need up to a year of time to complete telescopic follow-up of those objects," said Kirkpatrick.
Even if Nemesis is not found, the WISE telescope will help shed light on the darkest corners of the solar system. The telescope can be used to search for dwarf planets like Pluto that orbit the Sun off the solar system's ecliptic plane. The objects that make up the Oort Cloud are too small and far away for WISE to see, but it will be able to track potentially dangerous comets and asteroids closer to home.
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Nemesis
By Dr. Richard Muller
Note: My most recent paper (2002) relevant to the Nemesis theory is now available as a pdf document: Measurement of the lunar impact record for the past 3.5 billion years, and implications for the Nemesis theory, Geol. Soc. of America Special Paper 356, pp 659-665 (2002).
Origin of the theory
The "Nemesis Theory" was an outgrowth of the discovery of Alvarez et al., that the impact of a large (>10 km diameter) comet or asteroid was responsible for the great mass extinction that took place 65 million years ago.
Studies of the fossil record by Dave Raup and Jack Sepkoski shows that this was not an isolated event, but one of several mass extinctions that appear to occur on a regular 26 million year cycle. Their original paper analyzed marine fossil families, and was published in the Proceedings of the National Academy of Science USA, vol 81, pages 801-805 (1984).
Studies of the fossil record by Dave Raup and Jack Sepkoski shows that this was not an isolated event, but one of several mass extinctions that appear to occur on a regular 26 million year cycle. Their original paper analyzed marine fossil families, and was published in the Proceedings of the National Academy of Science USA, vol 81, pages 801-805 (1984).
The original extinction data of Raup and Sepkoski are replotted in the following figure.
The vertical axis shows the "extinction rate." This was taken from the values given by Raup and Sepkoski for the percent family extinctions at each geologic boundary. In order to take into account the uncertainty in the boundary ages, each data point was plotted as a Gaussian, with width equal to the uncertainty, and area equal to the extinction rate. This plot thus represents a statistical estimate of the extinction rate vs. time. The individual Gaussians for each stage boundary are shown as dotted lines. The extinction 65 million years ago is indicated with the little dinosaur icon.
The peak near 11 Ma is real, but exaggerated by the requirement that the plot go to zero at the present. Arrows are plotted every 26 million years. Note that many of these are close to the peaks in the extinction rate. This is the apparent 26 million year periodicity discovered by Raup and Sepkoski.
The peak near 11 Ma is real, but exaggerated by the requirement that the plot go to zero at the present. Arrows are plotted every 26 million years. Note that many of these are close to the peaks in the extinction rate. This is the apparent 26 million year periodicity discovered by Raup and Sepkoski.
There have been many statistical studies of these data. Although several studies indicate the periodicity is significant, not everyone agrees. I suggest that you decide for yourself. If you decide that the extinctions are not statistically significant, then there is no need for the Nemesis theory.
Additional work by Sepkoski shows that the periodicity is also present for fossil genera. His results were published in the Journal of the Geological Society of London, vol 146, pp 7-19 (1989). Figure 2 from this paper is shown below. Please note that the time axis has been reversed compared to that of the previous figure.
Plotted is the per-genus extinction rate (in units of extinctions/genus/Myr) for 49 sampling intervals. The upper time series (labeled Total) is for Sepkoski's entire data set of 17,500 genera, whereas the lower "filtered" time series is for a subset of 11,000 from which genera confined to single stratigraphic intervals have been excluded. The vertical lines are plotted at 26 Myr intervals.
The Nemesis theory was devised to account for this regularity in the timing of the mass extinctions reported by Raup and Sepkoski. According to this model, a companion star orbiting the Sun perturbs the Oort comet cloud every 26 Myr causing comet showers in the inner solar system. One or more of these comets strike the Earth causing a mass extinction. The Nemesis theory was originally published in Nature by Davis
Stability of the Nemesis orbit
There is a great deal of confusion among astronomers about the stability of the Nemesis orbit. Even many theorists who should know better believe that the orbit is unstable, and that the original Nemesis paper was in error. However detailed calculations by Piet Hut at the Institute for Advanced Study in Princeton show that the original estimate about the orbit were correct. Hut's results were published in Nature, vol 311, pp. 636-640 (1984). In our original paper we had stated that the orbit presently has a stability time constant of approximately one billion years. Many people naively assumed that this was incompatible with the 4.5 billion-year age of the solar system. But unlike the lifetime of a radioactive element, the lifetime of the Nemesis orbit is not predicted to be constant with time. In fact, Hut has shown that the lifetime decreases linearly, not exponentially, with age. The expected orbit lifetime when the solar system was formed was (presumably) about 5.5 billion years. When nearby stars pass the solar system, the orbit of Nemesis is given slight boosts in energy. The Nemesis orbit becomes larger and less stable. At present, the Nemesis orbit has a semi-major axis of about 1.5 light-years, and the orbit is expected to remain bound to the sun for only another billion years.
Note that the Nemesis theory predicts that the periodicity should not be precise. Perturbations from passing stars are not sufficient to disrupt the orbit, but they are sufficient to cause a slight (a few Myr) jitter in the interval between extinctions.
Why do so many people think the orbit is unstable? The basic answer is that scientists often don't have time to read the literature, so they depend on the summaries of others. Click here for more details.
The Search for Nemesis
Nemesis is most likely a red dwarf star, magnitude between 7 and 12. Virtually all such stars have been catalogued, but very few of them have had their distance measured. It is likely that Nemesis, if it exists, will be visible with binoculars or a small telescope.
We don't need a large telescope to find Nemesis. We need a small or medium telescope, and enough time to look at and analyze 3000 candidate stars. A series of images taken throughout the year should allow us to measure the large parallax of this star. We are also eliminating the stars measured by the Hipparcos satellite.
We began the search for Nemesis using the automated telescope at Leuschner Observatory. However this telescope was not designed for the heavy use it was receiving from this search and from our automated search for nearby supernova.
Fortunately, several all-sky surveys are underway that should find Nemesis in the next few years, if it is there, and rule out Nemesis if they don't. (Nemesis could hide if it were a black hole, but that is not very plausible.) These surveys include Pan-Starrs and the LSST.
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Huge Impact Crater Found in Remote Congo
Expedition confirms a meteor hit central Africa millions of years ago.
A computer model of the Luizi crater based on satellite data.
Diagram courtesy Ludovic Ferriere and SRTM/NASA
Victoria Jaggard
Published March 8, 2011
A circular depression deep in the Democratic Republic of the Congo (DRC)has been confirmed as the first known impact crater in central Africa, a new study says. The find brings the number of known meteor craters on Earth to 182.
The so-called Luizi structure was first described in a German geological report from 1919. But without further fieldwork, it was impossible to say for sure that the 10.5-mile-wide (17-kilometer-wide) feature had been made by a meteor impact.
On other planets, such as Mercury and Mars, it's easier to identify impact craters based only on their shapes, since these worlds no longer have geologic forces making major changes to their surfaces.
But on Earth, many older craters have likely been erased by tectonic activity or erosion, while others are so covered with dense vegetation or sediments, like Luizi, that they're almost impossible to spot without satellites.
What's more, the crater-like structures we do see may have been made by volcanoes, collapsed underground chambers, and other forces that have nothing to do with impacts, said study leader Ludovic Ferrière, curator of the rock collection at the Natural History Museum of Vienna in Austria.
"On Earth, to confirm it's an impact, you have to go in the field because you need evidence of high pressures and temperatures," Ferrière said.
Crater Expedition Had Brushes With Snakes, Poachers
The researcher first became interested in the Luizi structure after seeing satellite pictures published in the 1990s.
By studying the available satellite data, Ferrière and colleagues estimated that the structure has an elevated rim about 1,148 feet (350 meters) high, as well as an interior ring and a central depression.
But to truly confirm Luizi as an impact crater, the researchers had to mount an expedition to the politically tumultuous DRC. (Related: "Rare Gorillas at Risk as Rebels Seize Congo Park.")
"I was working for a year just to find a contact there, because you need a local person to help you find your way around," Ferrière said.
With funding from the National Geographic Society/Waitt Foundation program, Ferrière—then a postdoc at the University of Western Ontario in Canada—visited the crater site in June 2010 with colleagues from the University of Lubumbashi. (The National Geographic Society owns National Geographic News.)
"I flew direct to Lubumbashi, the second largest city in the DRC. From there we had to drive from the city to the crater," he said.
"I had looked at maps and planned a route before I left. But when I got there, my contact told me there is no bridge across part of my intended path. We had to take some crazy gravel roads with big potholes inside. These are not good roads to drive on, even with a four-wheel-drive car."
The team set up camp in a small village about 8 miles (13 kilometers) from the crater rim, recruiting two local guides/porters and a soldier to help them safely navigate the wild terrain.
"The crater is in a national park, and I thought it would be like the jungles of South America," Ferrière said. "Instead it was a tree savanna—a big plataeu with dry grass. The grass was sometimes more than a meter [3.2 feet] high."
Standing on the rim of the Luizi structure, Ferrière could see skinny trees that seemed to fill the depression, with the crater's distant edge rising like small hills.
Despite the remote, wooded terrain, "we saw no large animals, only snakes. But we did see a lot of remnants of poachers. Sometimes we'd come to a site and the doused fires were still hot."
Congo Rocks Had a Shock
Ferrière's team spent about a week at the crater collecting samples, which were sent back to the lab in Canada for analysis.
"I found so-called shatter cones, which are features in the rock only found in impact structures," he said. The nested, conical shapes in such features are evidence that the bedrock has been exposed to extreme pressure from a shock wave.
The crater rocks also contained an abundance of shocked quartz, a version of the mineral known to form only from impacts or nuclear blasts, Ferrière said.
"Everybody will believe me now, I think, that this is an impact site."
The scientists think the Luizi crater was made by a meteor more than 0.6 mile (a kilometer) wide that slammed into what is now the DRC at about 45,000 miles (72,000 kilometers) an hour.
For now it's unclear how old the crater is—the scientists can say only that the affected rocks are about 575 million years old, "but we know it's younger than that, because the rocks have been excavated," Ferrière said.
"It would be nice to do more fieldwork, because the shape of the structure with this inner ring can tell us about the exact formation process involved," he added. In the meantime, the researcher will continue to study the rock samples, now housed at the Vienna museum.
"There is still a lot to discover" about Luizi, he said.
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"Fresh" Crater Found in Egypt; Changes Impact Risk?
Geophysicists work in the newfound Kamil crater in an undated picture.
Photograph courtesy Museo Nazionale dell'Antartide Università di Siena
Andrew Fazekas
Published July 22, 2010
A small impact crater discovered in the Egyptian desert could change estimates for impact hazards to our planet, according to a new study.
One of the best preserved craters yet found on Earth, the Kamil crater was initially discovered in February during a survey of satellite images on Google Earth. Researchers think the crater formed within the past couple thousand years.
The Italian-Egyptian team that found the crater in pictures recently visited and studied the 147-foot-wide (45-meter-wide), 52-foot-deep (16-meter-deep) hole. The team also collected thousands of pieces of the space rock that littered the surrounding desert.
Based on their calculations, the team thinks that a 4.2-foot-wide (1.3-meter-wide) solid iron meteor weighing 11,023 to 22,046 pounds (5,000 to 10,000 kilograms) smashed into the desert—nearly intact—at speeds exceeding 2.1 miles (3.5 kilometers) a second.
There are no hard numbers for how many meteors this size might currently be on a collision course with Earth, but scientists think the potential threats could be in the tens of thousands.
Current impact models state that iron meteors around this size and mass should break into smaller chunks before impact. (Related: "Comet 'Shower' Killed Ice Age Mammals?")
Instead, the existence of the newfound crater implies that up to 35 percent of these iron giants may actually survive whole—and thus have greater destructive power.
Egypt Crater Still Shows Splatter
Estimating impact hazards to Earth isn't an exact science, since only 176 impact craters have been discovered so far, according to the Earth Impact Database, a resource maintained by the University of New Brunswick in Canada.
Most models are based on the number of impact craters on the moon, which has almost no atmosphere and so doesn't experience the same erosion processes as those on Earth.
"Current models predict that around a thousand to ten thousand such craters should have formed [on Earth] in one million years," said study co-author Luigi Folco, a scientist with the University of Siena in Italy.
"The reason why they are rare, however, is that, on Earth, weathering rates are high—small craters are usually easily eroded or buried."
Folco and colleagues were particularly surprised to find that the newfound, bowl-shaped crater has a prominent splatter pattern of bedrock shot up by the original impact blast.
Known as ejecta rays, these features are more often seen on other planets and moons with thin atmospheres.
The exact age of the Egyptian crater is still uncertain, the team reported this week in the online edition of the journal Science. Geologic evidence points to a relatively recent event, Folco said—although it's unlikely that any humans were around to witness the impact.
"During our field work we could see that some of the bedrock material ejected from the crater overlies prehistoric structures in the area," Folco said.
"We know from literature that the human occupation of this region ended about 5,000 years ago, with the onset of hyperarid conditions. Therefore we think that the impact occurred afterwards."
Meteor Threat Greater Than Realized
If future meteors like the Egyptian rock are more likely to remain intact, their energy on impact would be more focused, causing greater damage, said John Spray, a crater expert with the University of New Brunswick who isn't connected to the study.
Still, the probability of such a meteor hitting something critical for society, such as a major city, would be reduced, because the falling rocks would not be as spread out.
"Overall, the threat from impacts is probably greater than people realize, but historically there is very little information on this, and we just have not been collecting data for all that long," Spray said. (See "100 Years After Tunguska, Earth Not Ready for Meteors.")
"Our knowledge is very limited, so events such as these are quite important for helping us understand the frequency and nature of impacts that affect our planet."
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India Asteroid Killed Dinosaurs, Made Largest Crater?
October 16, 2009
The dinosaurs' demise may have been due to an asteroid double-whammy—two giant space rocks that struck near Mexico and India a few hundred thousand years apart, scientists say.
For decades one of the more popular theories for what killed the dinosaurs has focused on a single asteroid impact 65 million years ago.
A six-mile-wide (ten-kilometer-wide) asteroid is thought to have carved out the Chicxulub crater off Mexico's Yucatán Peninsula, triggering worldwide climate changes that led to the mass extinction.
But the controversial new theory says the dinosaurs were actually finished off by another 25-mile-wide (40-kilometer-wide) asteroid. That space rock slammed into the planet off the western coast of India about 300,000 yearsafter Chicxulub, experts say.
"The dinosaurs were really unlucky," said study co-author Sankar Chatterjee, a paleontologist at Texas Tech University in Lubbock.
Chatterjee thinks this second asteroid impact created a 300-mile-wide (500-kilometer-wide) depression on the Indian Ocean seafloor, which his team began exploring in 1996.
His team has dubbed this depression the Shiva crater, after the Hindu god of destruction and renewal.
"If we are correct," Chatterjee said, "this is the largest crater known on Earth."
Dinosaur-Killer Asteroid Boosted Volcanoes?
The Shiva asteroid impact was powerful enough to vaporize Earth's crust where it struck, allowing the much hotter mantle to well up and create the crater's tall, jagged rim, Chatterjee estimates.
What's more, his team thinks the impact caused a piece of the Indian subcontinent to break off and drift toward Africa, creating what are now the Seychelles islands (see map).
The Shiva impact may also have enhanced volcanic eruptions that were already occurring in what is now western India, Chatterjee added.
Some scientists have speculated that the noxious gases released by the Indian volcanoes, called the Deccan Traps, were crucial factors in the dinosaurs' extinction.
"It's very tempting to think that the impact actually triggered the volcanism," Chatterjee said.
"But that may not be true. It looks like the volcanism was already happening, and the [Shiva] impact just made it worse."
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"Dinosaur Killer" Asteroid Only One Part of New Quadruple-Whammy Theory
October 30, 2006
Offshore of Mexico's Yucatán Peninsula is a 110-mile-wide (180-kilometer-wide) crater dubbed Chicxulub, widely believed to be the site of an asteroid impact 65 million years ago that wiped out the dinosaurs (map of Mexico).
The mass extinction, thought to have obliterated two-thirds of the world's species in total, has been dubbed the K-T extinction because it bridges the Cretaceous and Tertiary geologic periods.
RELATED
But a single asteroid impact doesn't tell the whole story, says a small but vocal group of geologists led by Princeton University paleontologist Gerta Keller in New Jersey.
Keller and her collaborators believe that the Chicxulub impact predated the K-T extinction by about 300,000 years.
The dinosaurs, they say, were killed not by a lone asteroid strike but by the quadruple whammy of global climate change, massive volcanism, and not one but two gigantic collisions. (Related: "Yucatán Asteroid Didn't Kill Dinosaurs, Study Says" [March 9, 2004].)
Peeling Back the Layers
The complex scientific detective story involves tiny glass beads, the rare element iridium, and sediments that might be deposits from gigantic tsunamis kicked up by the Chicxulub impact.
Both sides of the debate agree that the glass was created when the Chicxulub event filled the atmosphere with vaporized rock that quickly condensed and rained to Earth as tiny spherules, about a tenth of an inch (1 to 4 millimeters) in diameter.
The opposing sides also agree that the iridium came from an iridium-rich asteroid.
The problem is that the spherules and iridium occur in separate layers of earth, or strata, separated by as much as 25 feet (8 meters) of intervening sediment.
Conventional theory says that the intervening sediment was laid down quickly by a series of tsunami waves created by the Chicxulub strike.
But a detailed analysis of the sediment layers suggests that the sediment was formed between two separate asteroid strikes, one that laid down the glass and the other the iridium.
To begin with, Keller says, the intervening sediment contains burrows from sea-bottom creatures that wouldn't have been able to dig if the seabed was being washed by violent tsunamis.
Keller's group also discovered a second layer of spherules about 13 feet (4 meters) below the disputed 25 feet (8 meters) of rock.
This strata, she says, represents the true Chicxulub spherule layer. Fossil evidence suggests that the lower layer of spherules was deposited 300,000 years before the K-T extinction. Overlying spherules were set down later, eroded from deposits elsewhere.
She has also found plankton-like fossils in the sediments above the lower-lying spherules, indicating a return to normal conditions for about 300,000 years after Chicxulub.
This suggests that Chicxulub, rather than causing widespread devastation, had essentially no long-term ecological effect, Keller says.
Geological evidence indicates that Earth was undergoing a large number of changes during the 500,000 years preceding the K-T boundary, she adds.
These included a global climate change that had slowly cooled Earth during the previous several million years. Then massive volcanism in India produced a rapid 7 to 13 degree Fahrenheit (4 to 7 degree Celsius) warming. (Related: "Did Huge Volcanic Blasts Snuff Out Dinos?" [August 23, 2005].)
The Chicxulub asteroid hit about a hundred thousand years after that, but the warming continued for another hundred thousand years, she says, until the Earth suddenly cooled again.
Then, she says, this already-stressed biota was hit by the second asteroid impact that produced the iridium layer. That was the last straw, culling out all but the species that were already adept at adapting to rapid climate fluctuations.
Keller's coworker, Thierry Adatte of the University of Neuchatel in Switzerland, adds that multiple asteroid impacts aren't as rare as people might think.
"We have found proof of a third one 200,000 years after the K-T boundary," he said. "We have a second iridium layer."'
In addition, he says, mass extinctions such as the one at the K-T boundary appear to require multiple causes.
"You really need a bad combination, like volcanism, climate change, and sea level fluctuations to have a major impact," he said.
Hotly Debated
But Keller's theory remains highly controversial.
"The whole issue hinges on the interpretation of the 'event deposits,'" sediment scientist Jan Smit of Vrije Universiteit in the Netherlands said by email.
"I think all evidence points to a single Chicxulub impact event that has caused tsunamis.... All the different sublayers ... are the results of the complicated tsunami waves' surges and associated currents."
In studying the impact's relationship to the K-T extinction, Smit adds, geologists need to look at regions distant from the Gulf of Mexico, where the geology hasn't been so strongly influenced by the direct effects of the impact.
"If you look elsewhere," he wrote, "only one impact can be documented."
But Princeton's Keller isn't likely to be deterred.
"This is more religion than anything else," she says. "A lot of people are so wedded to [the Chicxulub] theory that it seems that no evidence can ever convince them of anything else."
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