Thursday, September 30, 2004

A close brush!

Well, it wasn't THAT close, just a million miles away or so. But Earth played host to the asteroid Toutatis, which came within 1 million miles of the Earth yesterday. There were a few of the typical rumors suggesting that Toutatis would hit the Earth and destroy all civilization, but to my knowledge this did not happen.

Asteroids do hit the Earth from time to time, and this causes severe problems for anything living on the Earth. But asteroids do not careen randomly through the solar system. They obey Newton's Law of Gravity, just like every other planet, and so their paths are very predictable. The danger to the Earth is not from known asteroids, but from one we don't know about. Still, astronomers are looking for potentially dangerous asteroids, such as Spacewatch, and we'll find them if they are there.

I once had a person email me after the close approach of another asteroid; this person was scared to go to sleep in case an asteroid hit the Earth while she was sleeping. I tried to tell her not to worry; I don't know if she actually believed me. We need to be vigilant, but we don't need to worry about asteroids.

Toutatis (here in an image made with radar in 1992) swings by the Earth every four years or so. Due to the gravitational pull of planets, it is not possible to figure out if Toutatis will ever hit the Earth, but we do know that it's not going to hit in the next few thousand years. Enough time for another cup of coffee before astronomers go out to save the world. :)

Wednesday, September 29, 2004


This morning SpaceShipOne, a private spaceship competing for the Ansari X-Prize, rocketed 67.8 miles (108 km) above the Earth. This is a true victory for all the private companies working to open access to space. While I do not believe that routine passenger flights into space will happen for several years yet (an opinion not shared by Virgin Galactic), this is a major step forward in the private-sector space race.

My hat is off to pilot Mike Melvill, who stayed calm despite the spaceship performing 20 or so barrel rolls while the engine was firing. The previous test flight also had some control problems. This should remind us that space flight is dangerous. As various private companies continue there research and development, we should expect that there will be failures, and unfortunately those failures will cost lives. The pilots of these aircraft understand this risk, just like NASA's astronauts do. So hats off to these great teams!

I'll admit I didn't think the X-Prize could be won by its expiration at the end of this year, and we are one flight away from a winner.

Tuesday, September 28, 2004

Being prepared

Today'searthquake near Parkfield, California will be a big boon to scientists who research earthquakes. For decades scientists have known that the area where the earthquake occurred produces large earthquakes every 22 years or so, and they have placed a whole slew of instruments in the area to record the next earthquake. These pages detail the experiments in gory detail. Now the hard work and investments of time and money will finally pay off.

How does this relate to astronomy? Every 100 years or so, a star in our galaxy explodes, but no such explosion has been seen in over three hundred years! Astronomers are expecting that a "supernova" could occur at any time, and so have built up an armada of equipment that can start exploring the supernova as soon as it happens. It could be decades or centuries until we see a supernova in the Milky Way, but it could happen tomorrow. Like earthquakes, it is not possible to predict a supernova. And, like today's Parkfield earthquake, when a supernova does go off, we'll be ready and our time and money will pay off.

Monday, September 20, 2004

Go Weightless

I'm a bit surprised it has taken a company so long to offer weightless flights. For years astronauts have trained in NASA's "Vomit Comet". Parts of the movie Apollo 13 were filmed in such an airplane. Sign me up!

Thursday, September 16, 2004


One of the nice things about observing is getting to get back into nature somewhat. After all, we can't put an observatory in the middle of civilization. The lights from houses and cars, extra heat from pavement and roof tops all serve to hurt astronomical observations. So far this week we have seen several deer, including one that stood just outside our commons building, a couple of rattlesnakes, a black bear, and a zillion moths.

The Moon and Venus

This picture was taken on the morning of September 11, 2004 and shows the last quarter moon, Venus, and the morning twilight behind the silhouette of Mt. Wrightson south of Tucson.


A clear night at last, and we are working hard.

This is a picture of Tucson taken here from the observatory. This shows the problem of "light pollution." All of the light you see here is making our observations harder, but it is also wasted electricity. The light coming up to the mountain does not help the good citizens of Tucson to see any better. The International Dark-Sky Association explains how you can help keep skies dark and save on electricity costs without having to sacrifice the lighting that we need around our homes.

Wednesday, September 15, 2004

More Clouds!

We lost two nights of our three night run to cloouds/fog. The type of cloud is an "orographic" cloud, one that forms over a mountain. Moist air is forced up over the mountain, it cools, and loses the ability to hold moisture, so a cloud forms. This picture from John Weirich at the University of Arizona's Lunar and Planetary Labs shows an extreme example of such a cloud.

Tuesday, September 14, 2004

All fogged in

We got started at the telescope tonight, but at 10pm local time the humidity went up pretty high, and we had to close the dome. We don't need dew forming on expensive equipment! It's annoying though, to sit here in, see stars very clearly, and have to sit and hope the humidity drops.

Monday, September 13, 2004

Image of an Extra-Solar Planet?

Several news stories like this one have mentioned the recent announcement that a planet may have imaged around another star. If this is true, it would be the first direct picture of a planet in another solar system. So, is it true?

There are good reasons to be wary. Previous announcements have claimed to have imaged planets. Some have been shown to be background stars only appearing close to the "parent" star, others are still unconfirmed. This potential planet is somewhat exciting because the astronomers claim to have detected water. In order for water to form, the object has to be cooler than any known star.

So, how can we be certain that this is a planet orbiting another star? We could watch to see it orbit the parent star, but that could take hundreds of years. Or, we can wait a couple of years and look again -- stars all move relative to one another in the sky. If the purported planet and its parent star are moving the same direction at the same speed, then they are certainly travelling together. We must be patient!

This object raises some interesting questions. Assuming it is really a planet, the planet orbits a brown dwarf, a "failed" star that has too little mass to make its own light by nuclear fusion. But most astronomers would agree that a brown dwarf would not have enough material around it to form planets by "accretion" (Dust clumps together to form rocks, which clump together to form asteroids, which clump together to form planets.) So, if this is a planet orbiting a brown dwarf, it must have formed some other way.

Stars form when giant clouds of gas collapse due to gravity. It is possible that, when the gas cloud is collapsing, it will split into several smaller pieces. So it could be that the gas cloud that formed the brown dwarf split in two, with the larger clump forming the brown dwarf and the smaller lump the planet. But would you then call the "planet" a planet? It was made in a different way and likely has a different structure inside -- Jupiter probably has a center several times the size of the Earth made of rock, but a "planet" formed by splitting gas clouds would be almost pure gas, like the sun.

All this may be is a question of defining what a "planet" is. Of course, if the supposed planet turns out to be a star in the background, then the whole issue will go away. At least until the next possible planet is found!

A Well-Deserved Rest

I've taken the last couple of days off. I'd been observing for seven nights, so I've taken advantage of three nights off. Tomorrow I head back to the MMT to observe for three more nights. Then I have a month of normal hours before a few nights in Hawaii, along with a little snorkeling.

Thursday, September 09, 2004

More Observing Pictures

Here are some more pictures I took today while waiting for it to get dark:

Sunset over Baboquivari Peak west of Mount Hopkins.

This picture shows Kitt Peak, the observatory I was at last weekend, silhouetted against the twilight sky. The telescopes are barely visible as the bumps on top of the mountain. For a great picture, check this picture by Steve West out. It was taken with a C90 spotting scope and a Nikon 990 camera. Mine was taken with an Olympus digital camera and no scope whatsoever.

This is an image of the MMT taken as the dome was opening tonight. The mirror is 6.5 meters across (about 20 feet).

This is our control room, where all of our images are taken and the telescope is controlled. We can't see the telescope from where we sit. You can see some stars in the TV screen on the left of the shelf. At this point we were taking a long exposure.

Clear Skies!

Ah, we finally had some clear skies tonight. At sunset some thick clouds were overhead, blown off the tops of thunderstorms in Mexico. But by 10pm the clouds parted, and we spent the whole night taking lots of pictures. We are now one hour away from sunrise, and in about 10 or 15 minutes the sky will get too bright to do any more work. Almost time for bed!

The MMT on Mount Hopkins

So I've been observing at the MMT (used to be short for "Multiple-Mirror Telescope," though now there is just one mirror), which is part of the Fred L. Whipple Observatory on Mount Hopkins south of Tucson. Here are some pictures (click on each image for a better view):

The boxy building here is the MMT "dome." Why is it square and not a true dome? Because it is cheaper, and the stereotypical white dome is not necessary to get great pictures. Too bad the box is ugly.

This is a view of the neighboring mountain, Mt. Wrightson. We're located up high, 8400 feet (and 6000 feet above the desert below), so it is cool and wet enough for trees to grow. Mt. Hopkins is part of the Coronado National Forest.

A sight that strikes fear into the heart of the astronomer -- rain and storms. Luckily this storm stayed to the south of us, over Mexico, and we finally got to observe!

Wednesday, September 08, 2004

Continued Observing

I've been quiet the last few nights, as the weather has been great. So I've been working all night, taking lots of pictures. But now, on night five of seven, the clouds have come back in. So, I have had two good nights and three lousy nights so far. But this happens in astronomy.

Tomorrow I'll take some pictures of the control room, the telescope, and the dome.

Britain's Favorite TV Scientists

Who is your favorite fictional scientist? Mr. Spock on Star Trek? Dr. Who? How about this esteemed pair?

Monday, September 06, 2004

We're finally observing!

I lost the first two nights of my observing run to bad weather. We had clouds, rain and fog. But now the clouds have parted, and we are working.

So what am I looking at? I am taking pictures of open star clusters. I'm looking for white dwarfs, which are the remains of stars that have burned up all of their fuel. They are very faint, so we need crystal clear, dark skies. Finally we seem to have those conditions, so we're off to the races!

Saturday, September 04, 2004

Starry Starry Night -- Not!!

Well, I made it safely to Kitt Peak, but there's nothing exciting at the telescope tonight. Clouds and moisture from Hurricaine Howard off the coast of Baja California have reached us, so there is light drizzle and thick clouds. Compare this photo of the night sky taken tonight at Kitt Peak to this photo of tonight's sky at Mauna Kea. *sigh* Glad I brought a few movies along...

Thursday, September 02, 2004

Continuing telescope preparations

As I mentioned a few days ago, I am getting ready for a trip to the telescope this weekend. I'm driving west of Tucson to Kitt Peak National Observatory. So what have my preparations been?

I've been collecting a list of the stars and other objects I'm going to be looking at. I need to double-check the position of each object so that the telescope points at the right object. I also have made finding charts for each object. That way, when the telescope shows a field full of stars, I can make sure it is the right field of stars.

So, tomorrow at noon I'll gather up my charts and lists, my laptop and some snacks. I'll make sure the pet sitter is coming to feed my critters, and I'll head up the mountain. I hope to publish some pictures so you can get an idea of modern-day professional astronomy. We don't sit with a sketchbook at the eyepiece anymore!

Is E.T. calling?

A story in the New Scientist talks about a strange radio signal coming from space that may have some slight potential of possibly, maybe being from an alien civilization. Most of the high-profile folks involved in searches for extraterrestrial intelligence are very good scientists. Because these folks are being very carful about making any claims, it's clear to me that they are unconvinced. So it's nothing to get too excited about, but is certainly worth following up!

Wednesday, September 01, 2004

More Potential "Super-Earths" found

This article at is about two more Neptune-sized planets found around other stars.

What does this mean? Most importantly it represents that another technological hurdle has been cleared; searches for planets are more accurate than ever. With the ability to find smaller planets, we can not only find other Solar Systems, but also determine how many are like our own -- several planets in nearly circular orbits. If such solar systems are common, the chances are good that there are lots of solar systems with planets about the size of the Earth at the right distance from the star for life to form and be happy. If planetary systems like ours are rare, that doesn't bode well for a Universe teeming with life.

Tuesday, August 31, 2004

Death of Fred Whipple

This article is an obituary of Fred Whipple, a man who deduced that comets were "dirty snowballs" -- a collection of ice and dust -- rather than flying piles of sand, as had been thought. His book The Mystery of Comets was the first astronomy book I ever read. It came out in 1985 (when I was in 6th grade) as part of the run-up to the return of Halley's Comet. Whipple was a very intelligent, very practical man, and he lived to the ripe old age of 97.

Monday, August 30, 2004

Preparing to go to the telescope

It surprises many people to learn that astronomers do not spend every night awake at the telescope. Often, I have only a few nights every few months. The rest of the time is spent in my office at normal business hours. More on that in a future post.

This month I am very lucky and have seven nights on the telescope -- four nights at Kitt Peak followed by three nights at the MMT telescope. Both of these are in the desert around Tucson, Arizona.

Because I only have a few nights on each telescope, I need to make sure I am fully prepared. I have a list of the objects I want to observe, plus a list of objects to look at if the weather is only so-so (often my main target is so faint it is not possible to see if the weather isn't perfect).

A month ago I had to send an email to the telescope detailing how I want the telescope set up. Do I want any filters in the telescope? What types of things will I be doing? Do I want a room and food while on top of the mountain? (YES!!) This way the workers on Kitt Peak know how to get the telescope ready for me; they know to clean a room for me, and they know to put out extra food on the day I arrive.

More tomorrow on my preparations...

Saturday, August 28, 2004

Scientists go to the movies

I was looking for a good film to take in this weekend when I saw this story about scientist's favorite sci-fi movies. Sadly, though, I see that "Santa Claus Conquers the Martians" was left off the list.

Friday, August 27, 2004

Discovery of a "Super Earth?"

This story at talks about the discovery of a new planet around another star and calls the planet a "super-earth." The new planet is about the same mass as Uranus and Neptune or about 14 times the mass of the Earth. This makes it the smallest planet known around a normal star.

How do astronomers find planets outside our solar system? First we need to understand how planets are found around other stars. So far, no planets have been directly observed around other stars. Planets are too faint, especially since they are found very close to a bright star. Seeing a planet directly is like trying to look for lightning bugs around searchlights from several miles away.

So astronomers can only see the effect of the planets on their parent star. All planets have gravity and pull on their parent star. As the planet moves around the star, the star gets pulled in different directions. From Earth, we look for changes in the speed of the star --- the star will move toward us when the planet is between Earth and the star, and the star will move away when the planet is on the other side of its star. But these movements are tiny -- as small as 14 feet per second for this new "Super-Earth." It's impressive that we can measure such small movements from 100 trillion miles away! As massive planets have stronger gravitational pulls, they move the parent star more and are easier to find. That's why most of the planets known so far are larger than Saturn. But improved technology has allowed more accurate measurements, allowing smaller and smaller planets to be found.

As for "Super-Earth": every six days, the planet completes one orbit around the parent star. The small size of the star's wobbles tell us that this is much smaller than Jupiter. It's more like the mass of Uranus or Neptune, about fourteen times the mass of the Earth. This also makes it the smallest planet discovered around a normal star so far.

But "Super-Earth" is also interesting because we're not sure what it is made out of. The Jupiter-sized planets we have discovered around other stars are almost completely made out of gas -- there is no other obvious way to make such a big planet. But it is possible to make a planet as massive as the "Super-Earth" completely out of rock. So the "Super-Earth" may be the first rocky planet ever discovered outside of our solar system. And while Jupiter-size planets cannot have life like we know it, rocky planets could have lakes, oceans, and life.

Unfortunately, it is impossible right now to tell if it is made out of rock or not. And even if "Super-Earth" is made out of rock, it is far too close to its star for there to be any life. Its surface would be hot enough to melt most types of metal and would make a day on Mercury feel chilly.

But now that we can discover these small planets, it is only a matter of time before we find one about the right distance from a star for there to be liquid water. Then things will be really interesting!

Welcome to the Professor Astronomy Blog!

Welcome to Professor Astronomy's blog! Here I'll post snapshots of astronomer life, as well as notes and comments on news in astronomy and space science.

Do you have comments on what you see here? I've turned off commenting for the time being, but feel free to email me comments and questions at: . If you would like a good place to join in discussions on astronomy, I'd heartily recommend the discussion boards at Bad Astronomy web site.

And away we go!