Wednesday, December 30, 2009

Scientific American Jan 2010 & the Weak Nuclear Force

Contrary to the cover story in Scientific American's January 2010 issue, life would NOT be possible in a universe without the weak nuclear force, because then matter and antimatter would have completely annihilated each other, leaving no atoms to make life. Only the weak force treats matter and antimatter asymmetrically, allowing slightly more matter to develop in the first second after the Big Bang. Everything we see, and are made of, comes from that slight excess that the weak force enabled.

Saturday, December 26, 2009

Star Power: A Solution to Global Whining

This responds to a NY Times piece recently about global warming. $100 Trillion is per Scientific American article of November 2009.

Instead of rushing to spend $100 Trillion to install “renewable” energy, let’s spend far less and learn to make energy as nature does. Based on Einstein’s discovery, science promises energy sources that are cheap, clean, and abundant.

Thursday, September 3, 2009

Science and Religion are Compatible

As a scientist who strives to provide public access to science, I applaud the wonderful article by Lori Kozlowski about science and society in the Los Angeles Times on August 22, 2009, and wish to contribute some thoughts.

Contrary to what some scientists and some non-scientists stridently proclaim, I believe science and religion are compatible – both are organized efforts to find Truth. Best go to science to find the distance to the Sun, the age of the Earth, or similar questions whose answers are numbers. But science has not, and in my view never will, determine whether or not God exists, what is the purpose of human life, or to what ethical code good people should aspire. Science is incapable of answering such very important questions.

Science is not an obscure cult practiced by estranged people. Science is simply the extension of everyone’s innate curiosity. Children continually ask Why? They are born wanting to learn about and understand their world. Scientists are just people who never stopped asking Why?

Science should be for everyone. Just as you don’t have to be a great musician to appreciate great music, you don’t have to master complex math and technical jargon to appreciate the exciting discoveries of modern science. We live in the Golden Age of Science – more has been discovered in our lifetimes than in the entire prior history of mankind. We have found nature’s smallest parts and have seen out to the edge of the universe and back almost to the beginning of time. These exciting discoveries can be presented so that everyone can participate. I have given science talks at a wide range of venues from major universities to the Latina club of a local middle school. Audiences everywhere and of all ages have the same desire to understand more about their world. They just need information they can digest.

Science has not just increased our academic knowledge, but has also added to our wealth and welfare. A century ago, life expectancy in the U.S. was 47 years. In a single year, 40 million people died of the flu worldwide. Only 6% of Americans graduated from high school, and there were no iPods, DVDs, cellphones, internet, GPS, lasers, radio, movies, or television. In 100 years, our life expectancy has increased to 78 years, and of Americans over 25, 85% now graduate from high school and 27% earn college degrees. Most of these improvements are due to the advance of science and technology.

Looking forward, science is how we will reduce our dependency on foreign oil, mitigate pollution and solve global warming. It behooves the public to better understand science, so they can more knowledgeably participate in determining what sort of world we will leave to our children and grandchildren.

Sunday, August 30, 2009

EPA Should Not Deny Public’s Right To Know

An EPA decision to restrict greenhouse gas emissions may be of some benefit to the climate, but it certainly will substantially increase energy costs and unemployment as more jobs will be lost to countries without such restrictions. As a scientist and a taxpayer, I strongly believe the public has a right to a fair and open hearing and examination of the evidence supporting restrictions that will have such far-reaching impact.

As reported in the LA Times on August 25th, EPA spokesman Brendan Gilfillan claimed no public hearings were necessary because scientific evidence “overwhelmingly indicates that climate change presents a threat to human health and welfare.” However, nothing was said about any evidence that human activity is the cause of climate change, or that restrictions on the U.S. economy will solve this problem despite the most populous and most polluting nations continuing their rapidly increasing emissions.

I was particularly appalled by the reactionary comment of Brenda Ekwurzel of the Union of Concerned Scientists who compared a public inquiry to a witch hunt. Scientists who aren’t willing to publicly present their data and defend their conclusions should get out of science and become political lobbyists, no doubt that pays better. Oh, maybe some has already thought of that.


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Monday, June 1, 2009

Hubble Proved the Universe is Expanding

Edwin Hubble, after whom the newly repaired space telescope is named, used Henrietta Leavitt’s discovery to leap beyond the reaches of our galaxy. Hubble observed (before there were any space telescopes) that galaxies throughout the universe are moving away from Earth at velocities that are proportional to their distances from Earth; this is called Hubble’s Law.

We should not interpret Hubble's Law to mean that Earth is the center of the universe, nor that each galaxy is flying through space with a velocity that just happens to obey a certain formula. It doesn’t seem reasonable that each of the hundred billion galaxies just happens to have the right velocity. There must be some mechanism, some profound principle of nature, that choreographs this cosmic dance. The choreographer is space itself. What is really happening is that space is expanding and carrying with it everything it contains. As the space between galaxies expands, they move apart. Every location in the universe can lay equal claim to being the center of expansion – the universe expands in the same way as seen from every location.

Consider a simpler example. Imagine a strip of elastic tape with coins attached to it. If we stretch the tape, the coins will move apart. Now think of each coin as being a galaxy. Astronomers in each galaxy will observe all other galaxies moving away from them. They will observe galaxies that are twice as far away moving twice as fast, because there is twice as much tape stretching between them. They will discover Hubble’s Law. It isn’t really the galaxies (coins) that are moving, it’s the space (tape) between them that is expanding. In this example of a stretching tape, the expansion is in only one dimension. But, in our universe, all three dimensions of space are expanding at the same time and at the same rate.

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Wednesday, May 27, 2009

Hubble's Law Proves the Big Bang

What is the meaning of Hubble’s Law, which says that all the galaxies in the universe are moving away from Earth at velocities that are proportional to their distances from Earth?

Hubble’s Law leads us directly to conclude that the universe is expanding and that it had a beginning – the Big Bang!

To understand this, consider a simpler, down-to-Earth example. Imagine that we were on the top of the Seattle Space Needle (on a clear day in Seattle) using a telescope to look at traffic leaving the city for a long weekend. Also imagine that we discover that every vehicle on the road happens to be moving away from us at a velocity proportional to their distance (Hubble’s Law v = H d). Thus if we see a minivan 75 miles away going 25 mph, we know H = 1/3. And if we see a sports car 150 miles away, it must be going 50 mph per Hubble’s Law. If none of the vehicles changed their velocities, then where were they 3 hours earlier? Since the minivan covers 75 miles in 3 hours (25 mph times 3 hours), and it is 75 miles away now, it must have been at the base of the Space Needle 3 hours ago. Similarly, the sports car covers 150 miles in 3 hours, so it too was at the Space Needle 3 hours ago. In fact, if every vehicle on the road is obeying Hubble’s Law, then every one of them must have been in the same place 3 hours ago (probably when everyone got off work). This must be true because we can rearrange Hubble’s Law to read d – v/H = 0.

What’s all that got to do with the universe? If all the galaxies are moving away from us at velocities proportional to their distances (Hubble’s Law), as we observe that they do indeed, then all the galaxies must have been in one place at one time long ago – we call that moment the Big Bang.


video

Sunday, May 24, 2009

Hubble's Constant and the Expansion of the Universe

We discussed earlier how Henrietta Leavitt discovered how to use Cepheid variable stars as one of astronomy’s most precise “standard candles” to measure vast distances. Edwin Hubble built on Leavitt’s discovery to make some of the most important scientific advances of the 20th century.

Before Hubble’s work, astronomers thought our galaxy, the Milky Way, was the entire universe – they really didn’t have a concept of galaxies being separate structures within a larger universe.

Starting in 1919, Hubble began measuring the period and apparent brightness of numerous Cepheid variables in various so-called “nebulae” that were then thought to be fuzzy patches with “lots” of stars. In 1925, Hubble announced his findings. Using Leavitt’s work, he found that some of these “nebulae” were immensely farther from us than the rest of the Milky Way. And to be as bright as they appear to us, they must have billions of stars – they must themselves be separate galaxies, some comparable or even larger than our galaxy. Almost overnight, our concept of the size of the universe was literally blown away – its vastness was far beyond anyone’s wildest dreams.

In 1929, Hubble went even further. He combined his galaxy distance measurements with “redshift” measurements of the same galaxies. Redshifts are changes in the frequency of starlight that allow us to determine a star’s (or a galaxy’s) velocity. What Hubble discovered was that almost every galaxy was moving away from us, and for distant galaxies, their recessional velocity was proportional to their distance from Earth. In math, this is written v = H d, where d is the galaxy’s distance away, v is its recessional velocity, and H is a number we call the Hubble “constant.”

Based on Hubble Space Telescope data published by NASA two weeks ago, we now know H = 51,000 mph per million light-years, to a precision of 5%. (A light-year is the distance light travels in one year, about 6 trillion miles.) This means a galaxy 10 million light-years away is moving away from us at 510,000 mph, and a galaxy 100 million light-years away is moving 5.1 million mph.

The value of H has an enormous impact on the evolution of the universe. For nearly a century, measuring H has been one of the most important and most difficult tasks in astronomy and the source of great controversy. Edwin Hubble’s first measurements were about 7 times too high and had a very large measurement uncertainty. Even as recently as the 1990’s, some astronomers believed H was twice as large as what others thought. Using the space telescope named in his honor, Hubble’s constant has been measured with great precision.

Sunday, May 17, 2009

More on Hubble

Edwin’s Hubble’s famous discoveries about our universe were made possible by the remarkable work of Henrietta Leavitt. Overcoming her deafness and male chauvinism, Leavitt became the first famous American woman astronomer by solving one of astronomy’s greatest challenges.

After graduating from Radcliffe, Leavitt joined the Harvard Observatory in 1893 as a low-level technical assistant – women were not allowed to operate telescopes at that time. Her job was to count stars on photographic plates and measure their brightness.

Leavitt saw beyond her mundane task and discovered a special relationship for stars of a certain type — Cepheid variables. These are stars whose brightness waxes and wanes in a regular periodic fashion. Several types of stars vary in brightness, but Leavitt relaized that among Cepheid variables, the longer it took the star to go through its brightness cycle the brighter the star was at its peak. In fact, Leavitt demonstrated that from the length of a Cepheids’ cycle, its “period”, the star’s true, or “intrinsic”, brightness can be determined with great precision. Then by measuring how bright that star appears to us on Earth, its distance from Earth can be calculated. Leavitt discovered how Cepheids could become one of astronomy’s most precise “standard candles.”

As the notion of standard candles is of great importance in astronomy, it merits a bit more explanation. Imagine looking down a residential street at night and seeing a row of porch lights. If we knew that each house had a 100 watt blub on its porch, and we knew the distance to the nearest house, we could figure out the distance to every one of the other houses. We would measure how bright each porch light looks from our house and use the fact that the intensity of light drops with the square of the distance it travels – the light from a house twice as far away will appear one-quarter as bright. Astronomers can identify Cepheids, measure their periods, and, using Leavitt discovery, compute their distance.

This was huge! Measuring the distance to very remote objects has always been the most challenging task in astronomy. Thanks to Henrietta Leavitt, astronomers were finally able to measure vast distances – distances on a galactic scale and beyond.

With Leavitt’s discovery, Hubble forever changed our view of the universe. He recognized the importance of Leaviit's contribution and recommended that she be awarded the Nobel Prize in Physics. Unfortunately, Leavitt died in 1921, before the completion of Hubble’s work, and Nobel Prizes are not awarded posthumously.

Monday, May 11, 2009

Launch of Hubble Space Telescope Repair Mission

On Monday, May 11th, NASA launched the fifth and final repair mission for the Hubble Space Telescope (HST). Originally launched in April 1990, HST has provided some of the greatest advances in our understanding of the universe. The repair mission will replace failed gyroscopes, batteries and instruments, extending the life of the world’s most important telescope to 2014, and perhaps beyond.

The chart illustrates just how powerful the HST truly is. The chart shows how the amount of detail that astronomers could observe has grown over the last few centuries. Before 1609, astronomy was done solely with the human eye, which can resolve details as small as 1/50th of a degree. In 1609, Galileo pointed the first telescope at the heavens and was able to see about 600 times more than has ever been seen before. The world is celebrating the 400th anniversary of Galileo’s advance by declaring 2009 to be the International Year of Astronomy. As the chart shows, in the 400 years since Galileo, steady progress was made with ever more powerful telescopes. But all these pale in comparison to the dramatic advance achieved by the HST, which has provided almost 3 million times the information that can be seen by eye.

HST has opened a Golden Age of astronomy and opened our eyes to a more profound understanding of our universe and our place in it.

More on the telescope and the science later.

Now, we hope for the success and safe return of Space Shuttle crew Andrew Feustel, Michael Good, John Grunsfeld, Greg Johnson, Michael Massimino, Megan McArthur and Commander Scott Altman. These seven brave astronauts have trained for years and have accepted considerable risk to restore one of the greatest scientific instruments in human history.

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Monday, May 4, 2009

More about Cold Fusion

My earlier blog on cold fusion stirred up a hornets' nest of anonymous bloggers. Contrary to some of their allegations, I have no financial interest in “hot” fusion, nor do I work for an oil company. Indeed, I am retired and, unlike the cold fusion proponents on 60-Minutes, I have no financial interest in any specific company or technology in this field. Nor am I “merely” an academic. While I have physics degrees from Caltech and Stanford and was on the faculty of Harvard, I spent most of my career developing practical applications of advanced technologies, such as medical equipment that has dramatically improved patient care. I am sincere in wanting the best for our society, which is why I blog using my real name rather than hiding behind an alias.

I would be thrilled if someone developed a real “silver bullet” that instantly solved our critical energy and environmental challenges. I would also be thrilled if someone cured cancer, but I’m not rushing to buy snake oil from those eager to cash in on an unsuspecting public desperate for an easy cure.

If cold deuterium fusion were real it would be easy to provide definitive scientific proof, and that technology would be rapidly adopted. What will stop these people is not what I or anyone else says but rather they will fail because what they claim is simply not true.

I’ve read their statements and do not doubt that heat is released by their chemical reactions – there is nothing remarkable about that; matches do that also. Nowhere do they address the fundamental scientific issue that the energies required to fuse nuclei are vastly greater than those in any chemical reaction. They provide no evidence that helium is produced by the deuterium fusion they claim to achieve. There is no confirmation by an independent group that doesn’t stand to make money on cold fusion. As an old TV commercial once said: “Where’s the beef?”

Very promising, real solutions to our energy and environmental challenges exist, including solar, wind, and true fusion. All of these need major investments and decades to develop and implement. Let’s not let false hope and self-promoters divert us from investing our resources to achieve real progress – conservation, pollution-reduction, and new scientifically sensible energy generation.

Monday, April 20, 2009

Cold Fusion’s No Better Reheated

The announcement on the April 19th edition of 60-Minutes on CBS served the important purpose of presenting the enormous potential of fusion to provide virtually limitless, cheap, and pollution-free energy. Mastering fusion will be mankind’s greatest advance since mastering fire. While fusion is a vitally important objective, the so-called “breakthrough” announced by 60-Minutes is bad science and bad journalism.

The key claim made by the scientists 60-Minutes interviewed was that excess heat was generated by a reaction they say they do not understand. There’s nothing magic about reactions that release energy – candles generate more heat than the matches which light them. Every fuel we burn – coal, natural gas, diesel, gasoline – generates excess heat; that’s why we burn them. The only remarkable thing about this announcement is that the proponents acknowledged they didn’t understand it.

I once saw Siegfried and Roy make a tiger disappear five feet in front of me. That was very impressive, but I don’t think it was magic. The 60-Minutes announcement isn’t nearly as impressive, and it certainly is not new science.

Chemical reactions, such as the one discussed last night, release energy by rearranging electrons in molecules. The energy of any chemical reaction is therefore millions of times less than is required to change an atom of one element into an atom of different element. Chemical reactions can’t change lead into gold or deuterium into helium; only nuclear reactions have enough energy to do that.

If these scientists were serious about providing real proof of achieving cold fusion they should have shown evidence of helium gas being generated in the reaction. Fusion in the Sun and all other stars is based on hydrogen and deuterium nuclei being converted into helium. Detecting helium is easy to do and would provide a definitive test, as any competent scientist in this field is well aware.

If this were a sincere effort to advance energy technology and solve our critical energy and greenhouse gas problems, why didn’t the scientists present this definitive evidence?

If this were a sincere effort to inform the public of a vital field of scientific development, why didn’t 60-Minutes interview experts in nuclear physics? Promoting more “junk science” can only make the public understandably less interested in supporting real science.

Sunday, March 15, 2009

What’s Wrong with "Parallel Universes" on the History Channel

While the TV series The Universe has much valuable content and I applaud every effort to make science more accessible, occasionally this program is incomprehensibly wrong. The episode Parallel Universes is heavy with hyperbole, and a grossly incorrect claim. It states as a matter of fact that scientists have shot lasers beams across the universe to measure its global flatness. That is total nonsense.

Reflecting laser beams off the other end of the universe and back to Earth is ridiculous in itself – we can’t even do that to all the planets within our own solar system. And even if that were possible, it would take at least 27 billion years for the laser beam to return at the speed of light. While that would allow plenty of time for commercials, we would all have turned off the show long before.

This completely erroneous statement was part of a description of the measurement of the curvature of the universe by NASA’s WMAP satellite that is a spectacular scientific achievement deserving better reporting. Max Tegmark of MIT explained that the curvature of the universe can be measured by measuring the angles of a triangle that has a vertex at the Earth and the other two vertices at a very great distance. He said if the sum of the triangle’s angles were 180 degrees then the universe’s curvature would be zero and its geometry would be called “flat.” If the universe were curved (in a fourth spatial dimension) like a balloon, then the sum of the angles would be more than 180 degrees. This episode didn’t mention this but the sum of the angles could also be less than 180 degrees, in which case the geometry of the universe would be hyperbolic, like a four-dimensional potato chip. All that is fine. Where they went wrong was when the narrator said “to find out, they shot laser beams into space and made a giant light triangle.” They then cut back to Tegmark who said “Now we can tell and the measurement is in and it works beautifully. The angles add up to exactly 180 degrees.” Let me emphasize that Professor Tegmark was not the one who said lasers were shot into space to make a giant triangle.

The Universe claims to have a scientific adviser for each episode. I find it hard to believe that any such advisor reviewed the final cut of this and numerous other episodes.

Wednesday, March 4, 2009

What might happen if the heavens align on December 21st 2012?

Why didn’t the world end when the heavens were even more perfectly aligned in 1997?

Because space is vast, and everything in the heavens is so very far away.

As I discuss in Everyone’s Guide to Atoms, Einstein, and the Universe, there are four forces in nature:strong, electromagnetic, weak and gravity. The strong and weak forces have very short ranges—no larger than the size of an atomic nucleus—less than a trillionth of an inch. The electromagnetic force between large objects is extremely small because their electric charge is extremely close to zero. That leaves gravity. Gravity is intrinsically the weakest of all forces—the gravitational attraction of an electron to a proton is less than a trillionth of a trillionth of a trillionth of their electrical attraction. But, unlike electromagnetism, gravity is attractive for all forms of matter—it relentlessly accumulates. The 10 (raised to the 57) particles in the Sun pull on every one of the 10 (raised to the 51) particles in the Earth, and all those infinitesimal forces, all 10 (raised to the 108) of them, add up to one huge force that holds Earth in orbit. This makes gravity the most powerful and most important force of all. On a cosmic scale, it is gravity that controls the fate of everything.


So how much influence does the force of gravity from celestial bodies have on us? Below is a table of the strength of gravity that various heavenly bodies exert on us stated in g’s, the acceleration of Earth’s gravity at its surface (g = 32 feet per second squared).

Heavenly --------- Its Maximum Gravity
Body ------------ at Earth's Surface in g's

Earth-------------------- 1

Sun
--------------------- 0.000,63
Moon
------------------- 0.000,003,8

Jupiter
----------------- 0.000,000,03
Other Planets
--------- 0.000,000,02

Milky Way
-------------- 0.000,000,000,02

Since Earth’s orbit is slightly elliptical, the Sun’s gravity here varies between 0.000,59 g and 0.000,63 g. Even though Jupiter is 26,000 times more massive than our Moon, it is always at least 1600 times farther away, making its gravity never more than 1% of the Moon’s. Worrying about how the motion of the planets affects us makes no sense at all. The gravity from our immense galaxy, the Milky Way is about 200,000 times less here than the gravity of the Moon. Even though we are drawn by 100 billion stars, they are so far away that their effect is immeasurably small. And, since our distance to the galactic center is quite constant, even its minute force doesn’t change regardless of the orientation of the Earth, Sun, etc. Worrying about where the Sun will rise relative to the galactic center also makes no sense.

On Earth, the gravity of all other celestial bodies is virtually negligible compared to the Sun’s—that’s why Earth orbits the Sun and not anything else. The Moon’s gravity is 100 times less important, and everything else is 100 times less than that. Even the Sun’s gravity is 1600 less here than Earth’s own gravity. From the North Pole to the equator, Earth’s gravity changes by 0.5%, 0.005 on the above table. Changing one’s latitude is 200 times more important than the varying distance to the Sun, 10,000 times more important than the position of the Moon, and a million times more important than the position of all the planets.

No worries Mate.

Thursday, February 26, 2009

What's special about Dec 21st 2012?

So what’s so special about December 21st 2012?

Because of the gradual change of Earth’s rotational axis, on that date the Sun rise will be nearly aligned to our galaxy’s center. But why does the Earth axis gradually change to cause this alignment?

When objects spin, their rotational axes can be quite stable. A child’s top that spins on its point doesn’t fall over for a long time, even though the same top would immediately fall if it weren’t spinning. This is because spinning bodies have angular momentum which is conserved–the body will spin forever unless a torque is exerted on it by another body. This is what makes bicycles stable. We all know it is almost impossible to balance on a stationary bicycle. But, it’s easy to keep your balance on a moving bike because the angular momentum of the rotating tires and wheels provides stability.

The Earth spins on its axis once each day, making its axis stable (almost). Earth’s axis is titled by 23.5 degrees from a line perpendicular to the plane of Earth’s orbit. As the Earth orbits the Sun, its axis continues to point in the same direction (almost). That’s why we have seasons—why winter in the north is colder than summer. Because Earth isn’t a perfect sphere (it bulges at the equator due to its spin), the Sun and Moon exert a torque on Earth by pulling on that bulge. This torque causes Earth’s axis to precess, to slowly turn around a circle. A laser pointing straight up at the North Pole would sweep a circle across the heavens with one full turn every 26,000 years. It takes 71 years for the axis to turn by just one degree. That’s not much, but enough that ancient astronomers, including the Greeks and Mayans, detected this precession and measured its rate. As the axis precesses, the date of winter solstice slowly changes, as does the solstice Sun’s apparent position in the sky.

The Mayans believed that on 13.0.0.0.0 (December 21st 2012 to you) at winter solstice the Sun would align with the intersection of the central plane of the galaxy, the plane of Earth’s orbit, and the galactic center. With all that going for it, they expected all hell to break loose—this would be the End Date. Considering they didn’t have telescopes, the Mayans were great astronomers. But they were off a little. We were closer to this magic alignment in 1997 (off by only 1/60th of a degree) than we will be in 2012 (off by 1/5th degree), and we will be moving away from that perfect alignment for the next 13,000 years.

Since we survived the near perfect alignment in 1997, we should be OK (at least as far as this Mayan prophesy) for nearly 26,000 years.

But, can the alignment of the stars really effect us? More later.

Thursday, February 19, 2009

Is the world coming to an end?

At a recent talk, I was asked if the world would come to an end on December 21st 2012, as the ancient Mayan calendar predicted. I did some digging and found some things I hope you’ll find interesting.

In Mayan:
A day is 1 kin;
20 kin (20 days) are 1 uinal;
18 uinal (360 days) are 1 tun;
20 tun (19.7 years) are 1 kactun;
20 kactun (394.3 years) are 1 backtun; and
13 bactun (5125.3 years) are 1 epoch.

Their calendar apparently started on August 11th, 3114 B.C. (Some say it started two days later – why quibble?) and it stopped at the end of one epoch (13 bactuns).

Just for fun, I wrote a program to compute Mayan dates from our dates (Gregorian calendar dates). Today, February 19th 2009, is 12.19.15.1.14 Mayan standard time (12 bactun, 19 kactun, 15 tun, 1 uinal and 14 kin). Incidentally, counting all the leap years, that’s 733,456 days after January 1st of our year 0.

If anyone wants to know the Mayan for their favorite date, just let me know.

The Mayan End Date is 13.0.0.0.0, which corresponds to December 21st 2012 on our calendar. This is the day of the winter solstice – the shortest day of the year in the northern hemisphere. It turns out an unusual astronomical event will occur on that date. More on that later.