Friday, September 23, 2005

It's the time of the season...

Ah, fall is in the air, as yesterday afternoon the sun crossed the celestial equator to head south for the winter. Now it is officially autumn. Here in Tucson it feels like fall, as the temperature is only 99 degrees today.

By far the number one mistake the general population makes about astronomy is the cause of the seasons. A lot of people believe that the cause of the seasons is that the Earth is farther from the sun in the winter than in the summer, but that is wrong. In fact, the Earth is a million miles closer to the sun in the winter than in the summer. So what causes the Earth's seasons? It is the Earth's tilt.

Let's say it is a sunny but cold winter day, and you are outside and want to warm your face up a bit. What do you naturally do? You close your eyes and tilt your face so you are looking directly at the sun. When your face is pointed toward the sun, you are warmest. Likewise, the Earth is warmest when it is pointed toward the sun. The Earth is coldest when it is pointed away from the sun.

During winter here north of the equator, the North Pole is pointed as far away from the sun as it ever gets. At the same time, the South Pole is pointed toward the sun, so those lucky Aussies and Kiwis get summer. But by June, the North Pole is pointed as much toward the sun as it gets, and we northerners get to enjoy summer, while the southern hemisphere is plunged into the cold of winter.

So, keep this fact straight: The Earth's seasons are caused by the Earth's tilt, nothing else.

Wednesday, September 21, 2005

Mars is a changin'

In astronomy we are used to things not changing. There is the occasional comet or supernova or gamma-ray burst to liven things up, but most of the time a galaxy or star looks the same today as it did over 100 years ago. Most things just don't change over human lifetimes.

A recent press release from NASA's Mars Global Surveyor team reveals changes on Mars that have occurred just over the last few years. Gullies carved by evaporating dry ice appear in sand dunes, the southern polar ice cap changes shape from winter to winter, and even a meteor crater appears out of nowhere and then fades from view.

These pictures tell us that Mars is an active planet like the Earth, not a slow-changing world like the moon. This isn't surprising, as humans have seen huge dust storms appear on Mars and observed the changing polar caps for centuries. But to see the changes up close is, in scientific parlance, wicked cool.

Tuesday, September 20, 2005

Bad timing?

Yesterday NASA announced its plans for returning humans to the moon and later to Mars. This is an ambitious program, and it builds on our combined knowledge of space travel. There are also some ambitious plans that may or may not work, such as using ice that is thought to exist at the moon's south pole as water so moon crews can stay for months at a time. The cost for the return to the moon: $104 billion dollars between now and 2018.

That sounds like a lot of money, and it is, though probably not as much as people think. This adds up to about $9 billion per year. Compare this to costs in this year's federal budget: $31 billion for veteran's benefits, $40 billion for "administration of justice," $31 billion on environmental spending, $80 billion on education. So, the cost of a return to the moon is significantly less than these important costs.

I think NASA's in trouble, though, because of their timing. This announcement was made just days after the president requested another $60 billion for Katrina relief on top of a $400 billion federal deficit. Plus, we have two major military conflicts to pay for. So it is difficult to ask for even more spending to go to the moon.

The reason for the bad timing has to do with the federal budget process. This is the time of year when the 2007 budget is being prepared by the president for submission to Congress, so government agencies have to figure out what they want and need and justify those figures. It is just bad luck on NASA's part to time the announcement of the moon program right as unexpected major spending becomes necessary.

Thursday, September 15, 2005

Astronomy Ethics

Clay Bennett, The Christian Science Monitor

As mentioned in the last post, a huge ethical swarm is swirling around astronomy right now, centered on the recent discovery of large objects (maybe even planets) in the outer reaches of our Solar System. The issue is fairly complex, and I'll let the NY Times article speak for itself.

However, an interesting point is raised on when data should be released. Did the american team "hide" their discovery? Well, yes and no. They knew they had found a new object far out in the solar system, and from its brightness they knew it was quite big. So the find was very interesting, and lots of astronomers would be chomping at the bit to explore it. Understandably, the discoverers wanted to wait before announcing their find so that they could do some of the most obvious follow-up work themselves.

While this sounds selfish, I don't personally feel that it is selfish or unethical. Too many times I have seen press releases on discoveries that a little basic follow-up work found to be completely wrong or completely misinterpreted. Therefore I think it is scientifically responsible to do the first bit of follow-up work yourself, as long as, once you are confident in your find, you make appropriate announcements.

Currently I am working on several research projects with results that other astronomers will (hopefully!) find interesting, but I have not yet announced them. I want to make sure that I haven't made a big mistake first. I want to be correct as well as first. And these galaxies and planets will be around for thousands of years for further study. So am I being selfish or just responsible? I'll leave that up to you.

Tuesday, September 13, 2005

Scientific ethics

This article from the New York Times reports on an ethical brawl that has erupted in astronomy. I'm still trying to digest my thoughts on this, and will give my opinion tomorrow. In the meantime, it shows that even "pure science" is not immune from politics. How sad.

Monday, September 12, 2005

Solar Storms

The sun has been very active this week, causing major geomagnetic storms as a large sunspot group crosses the sun's face.

In the past several years the study of solar weather (more importantly, "Space weather" in the region of space around the Earth) has been recognized as an important area of study. Storms on the sun release large amounts of radiation and energetic particles, both of which can and have damaged satellites. With our growing use (and, dare I say, dependence) on satellites, from weather to GPS to phone calls, it is clearly important to learn to predict "space weather."

Space weather is also important for astronauts and cosmonauts on the International Space Station. Inside the station they are safe, but they cannot safely go outside during these storms. The radiation also affects Earth's upper atmosphere, making radio communications (such as military and jet aircraft radios) difficult if not impossible, especially near the poles. On the good side, solar storms make aurora (the "Northern Lights"), which are quite beautiful.

If you'd like to follow space weather, the Space Environment Center has more information than you could care to find!

Thursday, September 01, 2005

Clear Skies and Star Trails

We never did get to work last night because of ice on the domes, but it did clear off. My colleague, Ivelina Momcheva, took the following pictures with her digital camera last night. Great photography, Iva! Captions are above each photo; click on each photo for a better view!

This picture shows the Magellan Telescopes with the backdrop of the northern sky. The star trails here represent a one-hour exposure. What you are seeing is the rotation of the Earth, apparently causing the stars to move!

Now we swing around 180 degrees for a view of star trails near the South Celestial Pole. Notice that, unlike in the Northern Hemisphere, there is no bright "Southern Star" to mark due south, just a few faint stars. Notice also the beautiful colors of the stars. Our eyes only detect colors of the brightest stars, but they range the spectrum from red to yellow to blue.

This is another picture of the South Pole, but shorter. Two nearby galaxies are visible in this image. The large fuzzy one, just above the roof of the Commons Building, is the Large Magellanic Cloud, and the smaller fuzzy patch near the top of the image is the Small Magellanic Cloud. These galaxies are 200,000 light years away, yet easily visible to the naked eye in dark skies!

This picture shows the southern sky, along with the glow of the Milky Way, the galaxy we live in. The yellow glow low in the sky are street lights in the city of La Serena, about 150 km (100 miles) to the south.

What could have been much worse

Ah, it is a beautiful night here. The Milky Way arches majestically overhead, the Southern Cross is low in the south, and the Magellenic Clouds are climbing upward in the sky. Alas, we are not working here at Las Campanas this evening. Last night we received 4-6 inches of snow, and while much of it melted today, the melt water froze on the domes at nightfall, and it is not safe to open up the domes or operate the telescopes. This happens, unfortunately!

With some time on my hands, I've been closely following the news about the aftermath of Hurricane Katrina. It is truly a horrendous national disaster, and I'd urge everyone to help out the best that they can, even if it is just donating money to relief efforts.

In spite of the horrible distruction and loss of life in Louisiana, Mississippi and Alabama, things could have been much worse. Thanks in large part to weather satellites, plenty of warning was available to help evacuate hundreds of thousands of people out of New Orleans and other affected areas. Imagine how extreme the loss of life would have been without such warning. Tens of thousands could have died, much like in the Galveston Hurricane of 1900. These satellites, along with many others studying the Earth and its environs, are direct benefits from our space program and space research. These benefits were not all that apparent in the early part of the space race, when the largest concerns were the potential militarization of space. So, while much of today's space research may seem like it has no direct bearing on us (how many times have I heard the comment, "Wouldn't we be better off if that money were spent here on Earth?"), we need to remember the tens to hundreds of thousands of lives that space exploration saved this week, even as we mourn the hundreds who perished.