Monday, June 27, 2005

Preparing for fireworks

On Sunday night, July 3 2005, NASA's Deep Impact spacecraft will crash into comet Tempel 1. The point of this mission is to see what comets are made of and how they are constructed. Telescopes across the western hemisphere will be pointing at the comet to try and observe the celestial fireworks and see what happens.

Before the exact timing of the event was scheduled, I was awarded time at the MMT telescope outside of Tucson, Arizona. I'll be looking at distant galaxies during most of my time, but I was more than happy to volunteer a few hours of my time to try and study the comet before Earth's rotation takes it below the horizon.

So now I get to spend time this week learning about comets and trying to figure out how best to observe the Deep Impact mission. I'll be asking the instrument on the telescope to do things it wasn't designed to do, so I hope it all works out! There will be a TV crew up on the mountains, and I'll be sure to report here what is going on as it happens. Stay tuned!

Thursday, June 23, 2005

Evening Planets

The planets Venus, Mercury and Saturn are currently putting on a great show in the early evening sky. From our view on Earth, the planets are the closest they'll be until 2030 (though in reality they are tens to hundreds of millions of miles apart).

Tomorrow night, the 24th, the planets will appear to be only 2 1/2 degrees apart, or about 5 times the width of the full moon. Venus is the brightest of the three. If you watch the planets over a few days, it will be easy to see them move relative to one another as their orbits carry them around the sun. Saturn will appear to sink closer to the sun, while Venus and Mercury are climbing higher in the sky.

Take a few minutes over the next few days and take in the spectacle. More detailed explanations and graphs can be found from the Sky & Telescope website.

Wednesday, June 22, 2005

Solar Sail Sinks

Yesterday, the Planetary Society, a private group interested in fostering space travel, attempted to launch a $4 million solar sail called "Cosmos 1" from a Russian submarine. Unfortunately the booster rocket failed, and the satellite never had a chance. So what is a solar sail? The idea is to use sunlight as a "wind" to push a spaceship through the solar system. Light, like wind, exerts pressure and pushes on objects. For us on Earth, this pressure is much, much, much smaller than the forces of gravity and friction that control our movement, so we don't notice it. But in space, this pressure can push objects around. (Just note that this is not the solar wind that causes aurora here on Earth.) A solar sail is a very large piece of light-weight material (just like a boat sail) that has a large area for sunlight to push on. The sunlight will slowly accelerate the spacecraft, allowing it to move around the solar system without the need for a rocket engine. Changes in the spacecraft's speed are slow, but they add up over time. And spacecraft can be made lightweight, since most of the weight of any spacecraft is its engine and fuel. This launch was an experiment to see if a solar sail can really work, and it is a shame that the sail never even had a chance to unfurl. I suspect that the Planetary Society will try again before too much longer to prove this fanciful technology!

Tuesday, June 14, 2005

Earth-like planet discovery

Yesterday the planet-finding team of Paul Butler, Geoff Marcy and Debra Fischer (among many others) announced the discovery of a planet with a mass of 6-8 times the mass of the earth orbiting a nearby star. The work, headed by team member Eugenio Rivera of Lick Observatory, has been submitted for publication in The Astrophysical Journal, one of the top astronomy journals.

Here's an FAQ about the new planet:

  • How far away is the planet? The planet orbits a star, Gliese 876, which is 15 light-years (90 trillion miles, or 150 trillion km) away.
  • How do we know the planet is there? The discoverers detected a wobble in the parent star caused by the planet's gravity.
  • Are there any other planets around this star? Previously, two Juptier-sized planets were known to exist around this star.
  • Is there any chance of life on this planet? Almost certainly not. The planet orbits very close to the parent star, about ten times closer than Mercury is to the sun. It's surface temperature is likely between 400 and 800 degrees Fahrenheit, or almost as hot as Venus!
  • Why is this planet exciting? This planet is hot enough that it very likely could not hold on to a large atmosphere. Most of the mass of Jupiter, Saturn, Uranus and Neptune resides in the atmosphere. For the new planet, most if not all of the mass is probably pure rock, like the Earth, Venus, Mercury and Mars. This would be the first planet outside the solar system known to be made of rock.

A caveat, though, is that the Geneva planet search team claimed to find a rocky planet last year (see my blog post on the "super Earth"). So one could argue (and I'm sure astronomers are!) whether this is the first discovery of a rocky planet around another star. The reality is that we really don't know what these two planets look like or are made of. Future space missions that will actually be able to take pictures of these planets will help us to tell how big the planets are, allowing us to tell if they are made of rocks or gas.

Monday, June 13, 2005

Am I blue?

A story posted on space.com talks about the "discovery" of blue galaxies in voids, or large regions of the universe that have few galaxies. The result itself, which you can read about in the article, isn't unexpected, but it makes for a good lesson on the structure of the universe.

Shortly after the Big Bang, the Universe was almost perfectly smooth, with "almost" being the key word. Some parts had slightly more matter than others, some had slightly less. Over the 13 billion years the Universe has been around, the extra pull of gravity in the slightly denser areas pulled much of the material in the universe over, creating a pattern of galaxies that looks like the foam in a bubble bath. "Voids" are the spaces in the middle of these bubbles -- there isn't much there!

Since galaxies in voids are alone and mainly untouched since they formed, studying these galaxies helps astronomers to understand how galaxies grow, form stars, and change when nothing else is around. Since most galaxies are not in voids, but live near other galaxies in groups (a handful of big galaxies) or clusters (a swarm of hundreds of galaxies), any differences between the galaxies in voids and all other galaxies are likely due to interactions between galaxies. This includes galaxy harassment and galaxy collisions.

Thursday, June 09, 2005

Albert Einstein Action Figure

This past weekend, I had family visiting from around the country. Why they came to the desert in the middle of summer is a question I can't answer. At any rate, I was given an Albert Einstein Action Figure. While I doubt kids are going to start playing "mad scientist" with these figures anytime soon, it is a cool addition to my office.

This year marks the 100th anniversary of Einstein's "Year of Miracles," when he published landmark papers on three fundamental areas of physics. For that reason, 2005 has been declared the "World Year of Physics". So feel free to celebrate appropriately; just remember Einstein's admonition not to drink and derive.

So what were Einstein's three big breakthroughs that year? The most famous is the theory of Special Relativity, which describes how the laws of physics seem to change as you get close to the speed of light, including his famous E=mc^2 equation. This is different from his theory of General Relativity, which deals with the warping of space time, black holes, etc. That theory came 10 years later.

Einstein's second big idea was on the "photoelectric effect." In short, Einstein discovered that light acted like a particle, called the photon. Scientists already knew that light also acted like a wave. Einstein's thoughts on the photoelectric effect helped lead to the theory of quantum mechanics, or how subatomic particles actually work.

Einstein's third big concept involved "Brownian motion." If you watch a speck of dust in a drop of water, you'll notice the dust move around randomly, even though the water appears still. Einstein suggested that this was due to the water molecules jiggling around, randomly pushing the dust in different directions. Einstein was able to calculate the size of water molecules from this information, and it proved that substances were made of atoms long before electron microscopes allowed us to see individual atoms.

You can read more about Einstein's Miracle Year at this site.

Tuesday, June 07, 2005

Snippits & Factoids

I took a nice long weekend, as family was visiting in town. So below are little facts and snippets I picked up over the last few days.

  • Unstuck! The Martian rover Opportunity finally freed itself from its sand trap. Look for more cool science from this sturdy explorer!
  • Icy lava -- Yesterday's Astronomy Picture of the Day shows a picture of Saturn's moon Enceladus (not to be confused with enchiladas, a tasty treat.) This moon may have volcanos that spew water ice as lava! I like this idea, as I have a minor interest in volcanology. For some reason, many astronomers seem to have additional interest in geology, and many geologists have an interest in astronomy. There must be some similarity between the fields that draws similar people.

Thursday, June 02, 2005

New Pictures From Mars

Today I found two new pictures from our intrepid explorers on Mars, the rovers Spirit and Opportunity. From it's vantage point mired in a sand dune on the plains of Meridiani Planum, Opportunity snapped this picture of our home, the Earth. On the date the picture was taken, April 29, the Earth was about 130 million miles away. Meanwhile, Opportunity's twin sister, Spirit, sent this movie of a dust devil crossing the floor of Gusev Crater. As a resident of the Sonoran Desert, I see quite a few dust devils, especially this time of year. Spirit and Opportunity have benefitted from the dust devils, which clean dust off of the rovers' solar panels and have helped the rovers to survive over one year longer than planned in the harsh Martian climate.

Wednesday, June 01, 2005

Astronomy in the news

See any news stories on astronomy in the paper or on TV this week? This week in Minneapolis, many astronomers from across the continent are gathered for the summer meeting of the American Astronomical Society (AAS). These meetings are held twice a year, usually in early January and early June. Astronomers at the meeting give short talks on their research, display posters with new results from their projects, renew friendships and collaborations, and live, sleep and breathe astronomy. The AAS also takes this opportunity to issue press releases on cool new research.

If any interesting news comes out, I'll be sure to comment!