This page from Sky & Telescope magazine presents some great pictures from yesterday's total eclipse of the sun. Dang, I wish I could have been there!
Thursday, March 30, 2006
Wednesday, March 29, 2006
This morning, many parts of the Earth (but not North America) were able to see an eclipse of the sun, and a lucky few people were able to see a total eclipse of the sun, where the moon blocked out the bright disk of the sun for nearly four minutes.
Total eclipses of the sun are rare, occuring about once every 1.6 years, and only visible from a thin ribbon of the Earth's surface. On average, every part of the Earth will see an eclipse every 300+ years, though sometimes a given spot may get lucky and see a total eclipse twice in a short span, or another spot may be unlucky and go for several centuries without an eclipse. During each total eclipse, much of the rest of the Earth can see a partial eclipse of the sun.
Yours truly tried to see a total eclipse from Germany in 1999. A friend and I traveled to Saarbrucken, on the border of Germany and France, and we climbed a small hill (I think the hill was actually in France) to watch with a crowd. We viewed the eclipse until it was about two-thirds of the way to totality (here is a picture I took through my telescope), a thunderstorm rolled in. We all got soaking wet but hoped for a break in the clouds. Unfortunately, at the exact time of totality, it was still cloudy. In a matter of a few seconds, it went from light to nearly dark, and two minutes later, the lights came up again, all while the sky was overcast. What a shame!
For those of us in the continental U.S., the next total solar eclipse on our soil will not be until August 21, 2017. Until then, you'll have to travel! The next total solar eclipse is not until August 1, 2008, and will only be visible if you are a polar bear, a Siberian, Mongolian, or visiting China.
Tuesday, March 28, 2006
It hasn't been the most exciting past few days, because I've been working on editing papers for publication. One has just about finished the peer-review process, while the other has gone through one of what is likely two rounds of review.
As I've said before, peer review is a necessary part of science. In both of these papers, the reviewer has brought up points I wouldn't have otherwise considered. So, although editing, re-editing, and proof-reading manuscripts is almost (but not quite) as exciting as watching grass grow, it is necessary.
But to finish revisions of two papers is a first for me. Now for a well-deserved (at least in my opinion) break.
Monday, March 27, 2006
This week's Time magazine cover story deals with the sensitive issue of global warming. This issue highlights the ever-present and thorny issue of the overlap between science and politics. In recent months, a NASA employee has accused NASA of intimidation, scientists have declared that the Bush Administration distorts science, politicians have stated that the destruction of New Orleans during Hurricane Katrina was unforseeable, while scientists point that such warnings have been made for years, and on, and on, and on.
The truth is in between those two extremes. The vast majority of scientists are strongly driven in their research by a desire to determine the facts of science. But, like everybody, we have our own opinions, and it is true that many scientists (at least at universities) have a liberal political bent (but this is not true of every scientist -- I know of many strong conservatives among my colleagues). The trick is teasing apart facts from opinion. And this is hard!
For example, in the global warming debate, it is indisputable that, over the last couple of centuries, the average temperature of the Earth has been increasing. It is also indisputable that the atmospheric concentrations of "greenhouse gases" are increasing. And the vast majority of scientists (including myself) believe that these two are linked, though this is not proven. The burden of proof in science is steep and would likely require many more decades of research -- but do we want to wait that long?
In global warming, the politics starts to creep in as we go beyond these points. What will the effects of global warming be? The atmosphere and weather are complex (do you trust the weather forecast for ten days from now? I don't...). Many scientists claim the polar ice caps will melt completely, some claim that they will grow and start a new ice age, and some claim both will happen. Will Europe have record warm temperatures or record cold temperatures? Will the western U.S. have drought or record rain? Scientists argue about each of these, as well as many more points.
BUT a point that the public and politicians on both sides of the aisle often fail to see is that all of these arguments are not about the reality of global warming, and all of these possibilities will greatly affect humans across the globe. And this is why so many scientists vocally support reducing greenhouse gas emissions, stopping the deforestation of the Amazon, and other such "environmentalist" views.
So the next time you hear politicians talking about science, or scientists speaking politics, stop and think critically about what you hear. What is hard science and what is personal opinion?
Tuesday, March 21, 2006
Feel free to groan after that title. Sorry for the bad pun (well, not really).
People often wonder what function astronomy performs for the betterment of society. While I can toss off many reasons from the abstract (like the study of the unknown) to the concrete (like advances that have resulted in everyday technology), today we'll look briefly at astronomy and the arts.
Many artists (and I mean the term broadly -- from language arts to fine arts and everything in between) use astronomical events as inspiration. In recent years, some astronomers have been researching these inspirations and have been surprised at both the level of detail captured by the artists or lost details that can be gleaned from the work. In the last few years, I've read articles that have determined the exact date and time that an Ansel Adams photograph "Autumn Moon" was taken, determined the inspiration behind the red sky in Munch's "The Scream," and even determined that an appearance of Venus in "Harry Potter and the Order of the Phoenix" thought to have been impossible is actually possible (although we still question whether J. K. Rowling knew it was possible or got lucky).
In this article on Sky & Telescope's website, astronomers have determined both the identity of the yellow orb in Munch's "Girls on a Pier" (it is the moon) and explained why the reflection of the moon is not seen in the water (the house blocks the moonlight from reaching the water but not the viewer).
Monday, March 20, 2006
Spring arrives today at 1:26pm EST. Congratulations on making it through another winter! And for those of you where it is snowing today, I feel your pain. We have some of the first snow of the year on the mountains around Tucson today!
At the start of spring, the sun is directly above Earth's equator, and will continue to appear higher and higher in the sky for those in the northern hemisphere until the first day of summer. For anybody south of the equator, though, it is time to start waxing your snow skis and preparing for winter!
Last week I talked about how new results from the Wilkinson Microwave Anisotropy Probe (WMAP) find that the first stars formed about 400 million years after the Big Bang, and that this was the major result from the newest data. So, boy, was I surprised when all the press stories talked about how the new evidence supports the theory of inflation.
Inflation in astronomy has nothing to do with the value of the dollar (though some would say it explains how the costs of rocket launches seem to be much more than the first estimates). Astrophysical inflation explains a phenomenon that may have occurred in the tiniest fraction of a second after the Big Bang -- we are talking one ten-millionth of a billionth of a billionth of a billionth of a second (1x10^-34 seconds, for those of you who can read scientific notation), and lasting until the universe was only one hundred thousandth of a billionth of a billionth of a billionth of a second (1x10^-32 seconds). I hope I got those billionths and millionths correct!
During this time, the Universe expanded faster than the speed of light (don't worry, it is allowed by Einstein! Just trust me, you don't want me to try and explain it!) from a size much smaller than an atom to something about the size of a grapefruit. (During such a time, a ray of light would only make it about one billionth of the way across the nucleus of an atom).
As the Universe stopped inflating this rapidly and settled down to a more leisurely speed-of-light expansion, some tiny imprints of this transition would be left on the universe. And it is these imprints that WMAP supposedly saw in its data.
If this result holds, it marks a big victory for the theory of inflation. Until now, inflation worked great at explaining what we already knew about the universe, but none of its predictions had been tested. Any scientist worth her salt knows that until a theory makes predictions that hold up under testing, that theory is nothing more than a good idea. It is almost always possible to make theories that can explain what we know, but a correct theory can also explain what we don't know about. And it looks like inflation has possibly passed its first true test. If you would like to know more about the theory of inflation and aren't scared of a little physics jargon (probably introductory college physics level), check out this article.
Thursday, March 16, 2006
Today, WMAP announced results from three years of data collection, after an additional year of data analysis. The new information deals with "polarization" of the microwave background. Polarization of light indicates that the light bounced off of something. This is why polarized sunglasses are so nice -- they cut down on the polarized light glare from sunlight reflecting off the trunk of the car in front of you.
In the case of the cosmic microwaves, the polarization indicates that the light bounced off of electrons in the early universe. Right after the Big Bang, the whole universe was a very hot, glowing mass of atoms. After the Universe expanded for about 400,000 years, this soup of atoms cooled off enough to release the light we see now as microwaves. At some point, the first stars and quasars formed, releasing energy that warmed many of the atoms back up. We call this event "reionization," because the light energy from these stars and quasars removed electrons from the atoms in deep space for the second time in the history of the universe. These electrons, freed from their atoms, were now capable of reflecting the cosmic microwave background and polarizing it. And now, over 13 billion years later, WMAP has been able to detect the signals of reionization.
These signals tell us that the first stars in the universe formed 400 million years after the Big Bang (or 13.4 billion years ago). For those of you who understand the concept of "redshift," the redshift of reionization was between 7.3 and 12.1, with a best estimate of 9.3.
Anyway, we now know with much more certainty than ever before when the first stars in the Universe formed. Congratulations to the WMAP team for the results of their extreme efforts in analyzing data!
Wednesday, March 15, 2006
I am back home after spending all but 3 days of the last 3 weeks on the road. In that time, I have been in three countries, six states, been in hotels in five cities (staying with relatives a few other nights), and adding many frequent flier miles.
It is always hard to get back in the swing of things after such a trip. There are emails I have ignored, expense reports I need to fill out, and the problem of trying to remember exactly what I was doing before I left town. So, for today, I started the computer working on a couple of big jobs so that I could at least tell myself I was working on science.
It is nice to be home, though!
Friday, March 10, 2006
Yes, I know that Blogging has been light, but currently Professor Astronomy is currently 1650 miles (about 2650 km) away from the warm, sunny Sonoran Desert (where it is finally threatening to rain and a snow advisory has been issued). In the past 3 days, he has put 500 miles on a rental car, with 500 more to go in the next few days. So, hang tight, he will be back.
And, boy, is there a story of travel adventure to tell! ;)
Wednesday, March 01, 2006
The lack of blogging in the past few days has been due to some adventures in travel. Two delayed flights, two unexpected nights in hotels, and many other adventures later, I have arrived in Hawaii to observe with the Keck Telescope.
The only problem is the weather. The picture above is a webcam image taken late this afternoon from NASA's Infrared Telescope Facility looking at the Keck Telescopes (which I am supposed to be using). The bright object is the sun, with the streak being an artifact caused by the glare of the sun overwhelming the camera. But the grey things in the sky are clouds, the bane of the astronomer's existance. Right now, though it is dark, it is foggy and below freezing on the mountain, so ice is forming on everything up on the mountain. Needless to say, we will get nothing done tonight.
So, what happens when the weather gets us? It is our tough luck. We do not get extra telescope time as compensation. Weather is an occupational hazard. So, next year we will ask for more telescope time and try this again!