Thursday, April 30, 2009

If you give the control room mouse a cookie...

Prebles Meadow Jumping Mouse

Image Credit: US Fish and Wildlife Service
Those of you who follow my Twitter feed know that I haven't been alone in the control room on this observing run, I've been sharing it with a mouse. The mouse has been running back and forth most of the night each night, getting into the garbage can and scrounging for crumbs. I am not afraid of mice, but they are dirty, carry disease, and like to chew on things like computer wires. So, I told the mountain staff about the mouse. They said they knew about it, and that some of the observers even feed it. No wonder it doesn't seem too scared of me.

Next visit, I'll bring my cat. But, for the time being, I penned a poem about the mouse, stealing the title from the popular children's book:

If You Give The Control Room Mouse A Cookie

If you give the mouse a cookie
Like the kind you'd leave for Santa,
The mouse will give you droppings
And a virus we call "Hanta".

If you give the mouse a pretzel
Or some chips or popcorn,
Under three weeks later
More mice will be born.

All those baby mice will grow
And after food inquire.
And what could be more tasty
Than the dec motor's wire?

Then your telescope will break,
and you'll have to call Dave Doss,
Who when he hears you fed the mouse
Will be a little cross.

Then you'll lose your data,
And your papers go undone,
And without those publications,
The NSF won't fund.

Without funds there's no tenure,
And the bank will take your house.
So please clean up all your crumbs,
And do not feed the mouse.

Poetry like this means it's just a matter of time before I become the U.S. Poet Laureate. Probably just as likely as becoming a Nobel Laureate.

(FYI, the "dec motor" is the motor that moves the telescope north and south, and David Doss is one of our fine observing support staff here at the mountain)

Staying awake

If there's one part of my life where I can feel the effects of time on me, it is on observing runs. When I started observing just 15 years ago, staying up through the night was pretty easy, even on the long winter nights. That's a useful skill for an observational astronomer.

But as time has gone on, I find it harder and harder to stay awake all night. On this observing run, from twilight to twilight is only a smidge over nine hours, and yet I'm struggling to make it through the night. I've had more than my share of caffeine, done some calisthenics, and even rehearsed some music for a vocal concert I'm part of this weekend. Yet I can barely stay awake.

Thankfully, the telescope keeps tracking the sky and the camera keeps taking pictures with minimal input from me. Tonight has been one of the best nights of this observing run (which isn't saying much, since I've had only one other clear night in the week I've been up here), and I've been able to get good data in spite of my sleep-deprived state.

Wednesday, April 29, 2009

The most distant object ever seen

On April 23, NASA's Swift satellite detected a gamma-ray burst. It detects one every few days or so, so a new gamma-ray burst is not exciting in and of itself. But when astronomers looked at the burst with optical telescopes on Earth, they learned that it was the most distant object ever seen. Not just that, but it utterly smashed the previous record. Nancy Atkinson of Universe Today wrote a great article explaining this exciting discovery, so I'll be lazy and refer you to her post for more information.

One thing I appreciate about the story, and about this announcement in general, is that the story quoted the redshift of the object. So many astronomy press releases give distances in billions of light years. That practice makes sense for public news stories, because light-years have been the distance unit of choice for public news.

But as an observational astronomer, I rarely think in light-years for distant galaxies, I think in terms of redshift. Redshift is the amount that light has been stretched by the expansion of the Universe; redshift of zero means that the light is unaffected, redshift of one means that its wavelength has been doubled, redshift of two means it's been tripled, and so on. The redshift is the true observable, meaning that when we look at the light from distant objects, we measure this stretching. Astronomers then use models of the Universe to convert the redshift to light years.

Until recent times, astronomers were unsure what the proper model of the Universe was, and so the conversion from redshift to distance was uncertain. Due to the success of missions like WMAP, we now think we understand the fundamental structure of the Universe. But, by then, we'd gotten used to speaking in terms of redshift. So, if you talk about an object that is 12.6 billion light years away or 12.9 billion light years away, that doesn't mean much to my brain. If, instead, you talk about objects that are at redshifts of 6.5 and 8.2, I get it.

There's also always the possibility that we've made some fatal flaw in our understanding of the Universe, which would render our conversions from redshift to light years incorrect. I seriously doubt this is the case, and I'm willing to bet my friends' careers that we've nailed the conversion. But until we know for sure what dark matter and dark energy are, I'm not willing to bet my own career. :)

Congratulations to the astronomers who made this exciting discovery, and thanks a million for the redshifts!

Monday, April 27, 2009

A (mostly) clear night

video I've been observing all night, and for the most part it has been very clear. We did have some clouds when the dry line went through, traveling east-to-west. Anyway, our half-sky camera captured this, and I'm posting the resulting video. The video covers three hours, and you can see the stars moving as the Earth turns, and clouds forming, streaming away, and dissipating as the dry line moved through. The camera is mounted facing south on the Harlan Smith telescope. At the start of the video, the constellation Leo is in the upper center, moving right. Later, Virgo and Bo├Âtes are entering on the upper left, and the head of Scorpius just starts to appear at the bottom left.

Sunday, April 26, 2009

Swine Flu: Don't Panic!

Swine flu has burst onto the news scene in the last few days, and it feels to me like the panic is starting already. Folks, start with the advice of Douglas Adams: Don't Panic!

The swine flu is simply a name for a strain of the flu that originated in pigs. The influenza virus seems to like to mutate into forms that can jump from people to pigs to birds and back again; when it does so, it encounters other versions of the mutated flu virus, which allow the flu to swap some useful genes around and come up with new forms. This swapping is essential to the virus; if it stayed the same, people, pigs and birds would become immune to the virus in pretty short order, and the virus would die out. In short, the flu virus is an excellent example of evolution in action, mutating until it gets a "beneficial" mutation. Of course, what is beneficial for the virus tends to be bad news for people.

Most varieties of the flu virus are pretty similar to one another. This helps keeps the flu from spreading too rapidly, because many people's immune systems recognize the virus as a potential enemy, and mobilize rapidly. But the new strain of the swine flu is quite a bit different than most strains of the flu, which is what makes it more dangerous. Our bodies don't recognize the danger as quickly, so more people get sick, which spreads the disease more quickly and to more people than a typical flu outbreak. This means that the people most venerable to the flu, children and the elderly, are more likely to be exposed, which can lead to many more deaths than in a normal flu outbreak.

But you don't need to take draconian steps to protect yourself and your family from swine flu. The best protection you can take involves very basic things that your mom probably told you many years ago: wash your hands often, avoid large gatherings of people if you can, stay home if you are sick, go to the doctor if you come down with flu symptoms, and if you have to sneeze, cover your mouth.

Panic, on the other hand, doesn't do any good, and can do a lot of harm. Don't panic. If you come down with a little runny nose, don't go to the doctor and demand Tamiflu (or, worse yet, antibiotics, since the flu doesn't respond to antibiotics). If you are really sick, then yes, go to the doctor, and let her figure out what, if any, medication you need. If you aren't that sick, don't go to the doctor -- leave the appointment open for someone who really needs it. Besides, at the doctor's office, you're likely to run into people who are quite ill, and then you've been exposed to worse illnesses.

Other types of panic, like keeping your kids home from school, or boarding up your windows with all the plastic sheeting that Homeland Security advised us to buy several years ago, also cause more harm than good. The Centers for Disease Control (CDC) is constantly working on contingency plans, and they'll close a school if it is dangerous for the kids. The CDC is also the place to go to find more information about what you should and shouldn't do.

Swine flu has the potential to be a serious disease, and we shouldn't downplay its severity. But, again, panic is far worse. Stay informed, maintain personal hygiene, and go to the doctor if you are sick with the flu. Those few steps will go a long way toward combating the swine flu.

For more information on the swine flu, start with these two websites from the Centers for Disease Control:

P.S. My uncle, a retired hog farmer, would be upset if I didn't also mention that YOU CANNOT GET SWINE FLU FROM EATING PORK. So, if you like to eat pork, go ahead and enjoy.

Astronomy Week starts Monday

I was listening to the Marketplace podcast, a daily business and economics show produced by American Public Media, while I was watching the clouds fail to drift by earlier this evening. Toward the end of the podcast, during the upcoming events calendar, I did a double-take when I heard that next week is Astronomy Week. I didn't know that, and I should!

It took me a while to track it down, but next week is indeed Astronomy Week, sponsored by the Astronomical League. You can read about Astronomy Week, Astronomy Day (May 2), and world-wide events celebrating those days on this website.

While we are on the subject, you all remember that this entire year is the International Year of Astronomy, right?

And how about taking my poll on the IYA over on the right while you're at it?

I specifically requested clear skies in my proposal

Image Credit: McDonald Observatory

This week I am at McDonald Observatory, using the Otto Struve telescope to look at white dwarfs. Those of you who follow me on Twitter know that I've been whining about the "ongoing advection of Pacific moisture", as the National Weather Service so succinctly calls the stream of clouds coming up over western Texas last night and tonight. The image above is captured from our all-sky camera (which we'll put up on the web for everyone eventually), and it shows some of the better weather of the past two nights. You can actually see a few stars peeking out from behind the clouds.

Weather is one of the more frustrating parts of astronomy. I've had to sit on mountain tops through snowstorms, rime (ice fog), hurricane-force winds, and thunderstorms, as well as many nice nights. Personally, my least favorite observing weather is high humidity. It can be a clear night, with very steady skies, yet if dew is forming, you have to shut the telescope to protect it and the electronics from dew.

The problem with bad weather isn't just that we can't take data, after all, the stars will still be there tomorrow in all but the rarest cases. The problem is in how bad weather interplays with how telescope time is assigned.

Telescope time is assigned months in advance. We write short proposals asking to use telescopes for a certain project. A committee then reads all the proposals and judge each proposal on two primary criteria: is the science worthwhile, and can the proposed telescope time achieve those goals?

For the latter question, we have to explain in our proposals exactly how much telescope time we need, and how we came up with that number. For example, suppose we want to watch a planet transit in front of its parent star. These transits last a few hours, and you want to get a little bit of data before and after the transit. So, for a single transit, one night (7 or 8 hours) of data might be enough. But perhaps you need more than one transit. Maybe you think that the time between transits is slowly changing, maybe due to another planet pulling on the system with its gravity, and you figure that you need to see at least four transits to calculate that difference. So, you'll need four nights, one for each transit. And the telescope committee will be happy to see that you know exactly what you need, they like your science, and they give you four nights on the telescope.

When those four nights on the telescope come up, you go to the telescope and sit for four nights. On two of the nights you get good transit data, but then it gets cloudy and you get no data your last two nights. You need those extra two transits to do your project, but someone else is scheduled to come on the telescope the next night. You can't bump them off; your turn is over, and someone else gets their turn now. Essentially, you are in trouble; you can't finish your project until you get more telescope time, and the next set of time won't be awarded for four months, by which time your star is behind the sun for the rest of the year.

So you wait a whole year for your star to come around again, and you write your new proposal for telescope time, saying "I needed four nights, you gave me four, but the weather was bad on two, so I need two more nights to finish my project." The telescope committee gives you those two nights, and you go to the telescope, only to lose one of those nights to bad weather. Once again, you have to wait another year, and hope that nobody else is doing the same project and having better luck with the weather.

You might think the solution would be to build in time to allow for the weather. For example, if the weather is bad half of the time, you might ask for eight nights instead of four. But telescope committees don't like that. What happens if you get eight clear nights? You've wasted four clear nights that another project could have used!

You might think that you could try and pad your proposal, saying that you need eight transits, and so you need eight nights, though you know that you really only need four. If you can get away with this, it works, but telescope committees are pretty good at sniffing out padded proposals

So, what is an astronomer to do? There are many options, ranging from asking for what you need and hoping for the best, to padding the proposal and hoping you don't get caught. Myself, I try and set up multiple tiers for a program. For example, I may say that the best science I would like to do requires six nights, but I can still get useful information from four nights. That way, I'm being honest that I'm asking for more than the absolute minimum, but I'm pointing out that the extra couple of nights would not be wasted, but make the science all the better. This approach seems to work pretty well.

So, for this observing run, I asked for eleven nights to look at my white dwarfs, though I could still get useful information from six or seven nights. And I got eleven nights. Tonight is night 6, and I've had two good nights and four bad nights. So, I'm starting to get nervous. Any more bad nights, and it will be difficult to accomplish my project, and the weather is looking iffy for at least the next two nights. I need some good weather, and soon!

Thursday, April 23, 2009

Off to the observatory

Today I am driving out to McDonald Observatory for a week-long observing run to look at some pulsating white dwarfs. Hopefully I can avoid the stray thunderstorm and deer on the way out, and hopefully the armadillos will avoid me.

Wednesday, April 22, 2009

Global warming is not due to outer space

Global temperatures since 1900
Image Credit: NASA / Robert Simmon
Graph of solar irradiance
Image Credit: National Geophysical Data Center

As I promised yesterday, in honor of Earth Day, today I'll debunk some claims that global warming is being caused by something outside of the Earth. In fact, scientists are in agreement that global warming is caused by human activity. But, since I can speak with authority on astronomical issues, I'll stick to that for today.

Above are three graphs. The top two come from NASA's Earth Observatory website. The very top graph is the amount of carbon dioxide in Earth's atmosphere over the past century. Notice how fast it has been climbing, especially in the last 50 years or so. The second graph is a plot of average global temperatures over the same time period, set so that zero is the average temperature from 1951-1980. It also is going up dramatically, especially over the last 50 years or so. In fact, if we use records of global temperatures and carbon dioxide recorded in the ice of Antarctica, we find that temperatures and carbon dioxide mirror each other over the past 400,000 years. That's pretty strong evidence that the two are closely linked; there are many other experiments and measurements that prove that the link exists.

Despite this, some have claimed that global warming is due to an increase in radiation from the sun. The brightness of the sun is hard to measure, partly because the sun is so freakin' bright that it blows away all but the most carefully crafted instruments. We also have to measure the brightness of the sun from space, because Earth's atmosphere allows variable amounts of sunlight through, even on seemingly clear days. So, we only have records of the sun's brightness going back to about 1980, when satellites started measuring the sun's brightness.

The bottom graph above shows the brightness of the sun measured by different satellites (different colors of points). Notice that different satellites get different measurements! That just shows how hard it is to get an absolute number. But, since most of the satellites overlapped with one another, we can assume that measurements taken by two satellites at the same time should give the same answer, so we can shift those points to the same value. We astronomers would call this "relative photometry," and it is well-accepted practice. The black points in the graph of the sun's brightness show the relative photometry of the sun.

What you can see is that the relative brightness of the sun varies every 11 years; this is the normal solar sunspot cycle. The sun is a tiny bit brighter when it is more active, and a tiny bit fainter when it is less active. So, just compare the high points (from about 1980, 1990, and 2000) -- they are all at the same level! Look at the low points (about 1986 and 1997) -- those are also the same level. So, although the sun does vary in brightness, it does so in a regular fashion, and has not gotten systematically brighter over the last 30 years.

Now compare the sun's brightness to the graph of Earth's temperature, which shows an overall increase of about 0.5 degrees Celsius (about 1 degree Fahrenheit) since 1980. The Earth is getting steadily warmer, the sun is no brighter than it used to be.

This, folks, is pretty strong evidence falsifying the hypothesis that global warming is caused by a brighter sun. The sun is no brighter than it was 30 years ago, but the Earth is warmer than it was 30 years ago.

Now this doesn't mean that the sun doesn't affect Earth's climate. In the late 1600s, the sun went through an extended period of low activity called the Maunder Minimum, and the Earth did cool off by about 1 degree Celsius during this time. Also, over hundred million year time scales, the sun is getting brighter; we estimate that in just 1 or 2 billion years or so, the sun will become bright enough to evaporate Earth's oceans. But the sun is not more active than normal, and its gradual increase in brightness is far too slow to explain the Earth's current warming.

Other people claim that other bodies in the Solar System appear to be warming up, specifically, Mars, Jupiter, Triton (a moon of Neptune), and Pluto. But half of Jupiter's heat does not to come from the sun at all, and more rigorous studies show that the total amount of heat energy over Jupiter has not changed appreciably. Triton's south pole has just reached summer, which lasts a good 40 years, and so would be expected to warm up. Pluto gets much closer to the sun at certain parts of its 250-year long orbit; it reached its closest point in 1989. The extra warming from the sun melted some of Pluto's outer layers of methane ice into methane gas; methane gas is a known and very effective greenhouse gas, and so we'd expect Pluto to warm up even more once it has some methane. Over the next few decades, though, this gas should cool off as Pluto moves away from the sun, and freeze back onto Pluto's surface.

That leaves Mars. The evidence for global warming on Mars is that the southern polar ice cap has shrunk a little more each of the past three Martian summers than in the previous summer. Does this mean global warming is happening on Mars? The majority of Mars climate modellers say no, and that Mars may be cooler now than it was in the 1970s. The truth is, it is only in the last 15 Earth years or so that Mars has been under constant, close scrutiny by a flotilla of satellites; that adds up to about 7 or 8 Martian years. We've had better data on Earth for decades, and the Earth often shows short-term (few-year-long) climate swings (like El Nino). Long term monitoring of Mars's climate is needed to determine what it's long term trend is. We know the long term trend on Earth, it's up (see the graphs at the top again).

In short, there's no convincing evidence that global warming has causes related to astronomical phenomena, and, in fact, there is strong evidence to the contrary.

I wish I could say that global warming is not happening or is not caused by humans, and that we all can go on living our lives and not have to worry about it. Unfortunately, it is real, and we are the cause. I gain nothing from stating that fact.

But facts are stubborn things; and whatever may be our wishes, our inclinations, or the dictates of our passion, they cannot alter the state of facts and evidence.

The fact of global warming means that we all are going to have to make some tough and unpopular lifestyle changes. The sooner we start acting these changes, the less painful the costs will have to be. The longer we wait, the more expensive global warming becomes, the more drastically we have to act, and the more painful the choices we will have to make.

Tuesday, April 21, 2009

Waiting on Earth Day

Tomorrow is Earth Day, so I thought I'd write a few thoughts about that. But first, some seemingly-unrelated anecdotes. Bear with me; I'll get to my point at the end.

The movie Airplane! starts with a scene outside of LAX. A man flags down a taxi, and hops in. The taxi driver says, "I'll be right back," starts the meter running, and goes inside the airport. After chasing down his ex-girlfriend and having a long heart-to-heart talk, the taxi driver buys a one-way ticket to Chicago. At this point, the camera cuts back to the passenger in the taxi, who is still waiting patiently. At the end of the movie, after the plane flies to Chicago (at least 4 hours!), the camera cuts back to the guy in the taxi, where the meter now reads $113. The passenger says, "Well, I'll give him 20 more minutes, but that's it!"

A few weeks ago, I took my car in for an oil change. During the servicing, the mechanic told me that the battery was bad and needed replacing. Now, I'm normally very skeptical of what mechanics tell me during an oil change, and I get second opinions before getting any expensive servicing done. But I'd noticed that, on cold mornings, the engine would struggle to get started, and I'd noticed a few other electrical issues when the engine was off. Since my existing battery was still under warranty, I took it back to Sears for further testing. Sure enough, it was bad and needed to be replaced.

Now I could have waited until the battery completely failed to be certain that there was a problem, and not relied on mechanics who want me to spend my money there at the shop. However, Murphy's Law dictates that the battery would not have failed me on a Saturday morning when I just happened to be parked in the mechanic's driveway. No, it would more likely have failed on a drive through west Texas, where I'd have to pay for a 100 mile tow to the nearest shop and buy a battery at 3 times the price. So, instead of taking that risk of a much more expensive repair, I had the battery replaced at Sears, where the warranty covered half the cost of a new battery.

Another story: I grew up in rural Pennsylvania, where our house was supplied with water from a well. Due to the geology of the area, our well water was quite acidic (pH of 4, roughly that of soda pop). In the 6 years before I went to college, we had the bottom rust out of two hot water heaters. A plumber told us that this was due to the acidity, and suggested that we install a neutralizer and water softening system. This was very expensive, and the yearly maintenance on the system was expensive enough that it was cheaper to buy water heaters every few years. But we had other signs that not all was well with the plumbing. All of our sinks and tubs were stained green with copper that was being leached out of the pipes by the acidic water. Our chrome faucets tended to drip, and where the drips formed, the chrome had been eaten away. In short, it was just a matter of time (maybe a decade, maybe just few years) before the entire plumbing in the house would need to be replaced. But the plumbing had last for 30 years, and new plumbing would last at least as long, so the average yearly dollar cost may still have been less than the yearly cost of the neutralizing system. But my parents decided that the hassle of replacing the plumbing and the potential loss of our belongings in a flooded basement were not worth a lower average cost, and they payed through the nose to get the expensive water neutralizer and softening system. It cost a lot, and it was unclear how long we would have to wait to recoup the cost (if ever), but it saved us the huge mess of having to replace pipes, valves, faucets, and water heaters. (It turned out that some of these had to be replaced anyway, because we'd waited a little too long to buy the neutralizer, but we did avoid re-plumbing the entire house.)

What do these stories have in common? Each featured a person who had to make a decision on the cost of waiting before acting. The guy in the taxi was pretty stupid, as it wouldn't have cost him anything to flag down a different taxi, plus he wouldn't have to wait hours to get home. Fixing the battery in my car was pretty much a no-brainer, because the signs that the battery was failing were there, the cost of the repair was pretty cheap, and it undoubtedly saved my a big expense and hassle at some point down the road. The plumbing repair in my parents' house was a tougher call. In retrospect, it was obviously the right move, but at the time, it was a huge expense. The signs all pointed to that repair being the right thing to prevent a big plumbing disaster, but a lot of the cost-benefit analysis results were unclear if the only consideration were dollar costs.

As humans, we've reached a point of decision in regard to global warming. We can decide to do nothing, hoping that nothing will happen. That's like sitting in the taxi and hoping the driver will come back, when the driver's really on an ill-fated flight to Chicago.

We can also look at the huge costs of revamping our infrastructure to combat global warming. It's a big expense in the short term. Some people claim that the long-term costs of ameliorating global warming (e.g., higher energy costs for air-conditioning, costs of relocating agriculture from existing areas that will become to dry, costs of piping water to newly-arid locations, costs of wars and human resettlement due to climate change, etc.) will be less than the costs of trying to reverse global warming. In pure dollar amounts, maybe this is so, though I doubt it (I'd be willing to be my career that the cost of inaction will be many times the cost of present action.) When you add in the cost in human life and hassle to human beings, it's not worth it, in my book. It seems more prudent to bite the bullet and take the preventative measures before we have a huge(r) mess on our hands.

The signs that man-made global warming is real and is a threat are all around us. We can ignore it and hope that we are misinterpreting the signs, and we risk a flood of disasters or being left in the wilderness with no way out. Or, we can take steps now that, while costly and not able to prevent all problems, will prevent the worst-case scenarios. I vote for the prudent path.

So, do we wait and hope, or do we act?

Tomorrow, I'll shoot down some of the astronomy-related myths that global warming deniers spout out when they try to convince people to wait another 20 minutes, just in case the driver comes back.

Monday, April 20, 2009


This is a test of the emergency blogging service. Had this been an actual blogging emergency, this entry would contain useful content, or at least incoherent ranting.

Wednesday, April 15, 2009

Happy April 15

For U.S. citizens, today is Tax Day, the day we all grumble about all of the unnecessary and wasteful services that government provides, like defense, roads, police, schools, etc. Of course, if we canceled all that wasteful astronomy spending, you'd get to keep an extra $3.50 a month. (I'm being sarcastic...)

Today is also my grandmother's birthday. She's 84 years old today. Alas, she doesn't know it. She has been suffering from Alzheimer's Disease for the last 15 years or so, and the disease has advanced to the point that she can't talk and likely doesn't recognize many people, if anyone. But she'll enjoy the colorful flowers and balloons and the extra attention.

Before she retired, my Grandma was a case worker for the county welfare department. That was a thankless job; many recipients of welfare dislike the intrusion and paperwork (understandably; I would hate it too), and many in society unfairly disparage the welfare system. (It's not perfect, but what system can be?) But she knew she was doing an important job, providing the only support keeping many families and disabled people from the abject poverty that all too many people experienced during the Great Depression, which was raging throughout her childhood and adolescence. That same social safety net now protects her in the fading twilight of her life; I shudder to think of where she would be without Social Security and Medicare, as health care costs depleted her life's savings many years ago.

Tuesday, April 14, 2009

Writer's block

Sorry to have been quiet recently, I've been fighting a bout of writer's block. It's not a lack of ideas, it's just that none of them make for even mildly interesting entries. (Of course, this hasn't stopped me before). So, I'll just write a couple of sentences on each topic, and you can do some Google searching to fill in the blanks.
  • Coincidence? Last week many members of my family were cut off from phone service when a vandal snipped fiber optic cables. In one of the reader's comments, someone asked if it was "just a coincidence?????" that the cables were snipped during an ongoing contract dispute between AT&T and their worker's union. The relation seems plausible, but that doesn't mean that they're related. Coincidences, even those that seem unlikely, are extraordinarily common. Just because two closely-spaced rare events happen doesn't mean they're related, as shown in the film My Cousin Vinny (and some more reputable periodicals and books). In astronomy, we always have to be really careful about coincidences.
  • The case of the disappearing star Astronomers believe that supernovae are explosions at the end of the life of a star. These explosions can completely obliterate the star or leave behind a neutron star or black hole. In either case, once the explosion fades away, the original star should be gone. This disappearance had been confirmed in only one case, Supernova 1987A in the Milky Way's next door neighbor, the Large Magellanic Cloud. Now, Justyn Maund, a friend and colleague of mine, has shown that in two other supernovae, the original star has disappeared, too. Maybe it's not surprising, but it is important confirmation that our theories are right. (In none of the three cases has the remnant neutron star or black hole yet been seen; they are extraordinarily difficult to detect. But that will be another important test...)
  • Amateur astronomers saved our hides. Well, that may be a little strong, but they certainly have saved at least two major observing runs. Our local white dwarf research group has contacts with amateur astronomers in the Central Texas Astronomical Society(CTAS). They have been helping us for years, and we let them use our spare equipment. Well, on an observing run last month, our primary camera at McDonald Observatory broke in the middle of the night. In a couple of hours, Willie Strickland of CTAS had taken the spare camera off of their telescope, and I was able to get it to the mountain the next day, so we only lost one night to that instrument problem. After the observing run, CTAS member Dean Chandler was able to diagnose and fix the problem with a $10 spare part, which saved hundreds of dollars and weeks of time that it would have cost if we'd sent it back to the manufacturer for repairs. We greatly appreciate the time and effort that Dean, Willie, and other CTAS members have donated to our research work; we would be dead in the water without them right now!
  • There's a new poll off to the right asking how you are celebrating the International Year of Astronomy. Why not weigh in?

Thursday, April 09, 2009

Full moon

Yesterday evening I was at a choir rehearsal. One of our sopranos came in late, apologizing that she had stopped to watch the full moon rise through a thin layer of clouds.

I've heard people remark in years past how it always seems like there is a full moon pretty close to Easter; they marked it up to an amazing coincidence. In fact, it is no coincidence at all.

The Christian holiday of Easter is always held on the first Sunday following the first full moon of spring, where spring is defined to start on March 21. (For all of us except the occasional rogue curmudgeonly astronomer, spring is assumed to start on the Vernal Equinox, which is often not March 21, but usually this distinction doesn't matter.) The full moon was 5 minutes ago (by my watch), so Easter falls on Sunday. And, if the weather is nice, people enjoying the spring weather in the week before Easter will probably notice a big, nearly-full moon rising just after sunset.

Why is Easter set by the full moon and not by a specific date, like the Christian Christmas holiday? It's because the events celebrated by Easter occurred in the days following the Jewish holiday of Passover, so the Catholic Church set the date of Easter to mimic the timing of the Passover.

The Jewish Passover celebration is celebrated starting on the 15th day of the month of Nisan. The Jewish calendar is a quasi-lunar calendar, meaning that the months start at the start of the new moon. Since there aren't exactly 12 cycles of the moon in a calendar year, the Jewish calendar contains either 12 or 13 months, depending on the year, so that the months always roughly align with the same seasons. Since the month begins at the new moon, and the full moon is about 14 3/4 days after the new moon, the Passover feast always begins right at the full moon.

There's yet another complication. Eastern Christian churches, like the Greek Orthodox and Russian Orthodox churches, base their calculation of Easter on the Julian calendar, while western churches use the Gregorian calendar (what most of us consider "the calendar"; read here about the differences between the two.) These two calendars are 13 days apart (with the Gregorian calendar "ahead" of the Julian calendar), so roughly half of the time the first full moon of spring in the Gregorian calendar is one lunar cycle earlier than the first full moon of spring in the Julian calendar. This means that, roughly half of the time, the Orthodox Easter happens one full moon after the western Easter holiday. Confusing? Definitely. And then there's this year, when the Orthodox Easter is April 19, while the western Easter is one week earlier, on April 12. I don't know how that happened; I'm sure that is explained online somewhere.

The sum total of all of this means that even though the Christian and Jewish holidays are closely related, they often don't fall on the same date. Even more, even different branches of religion disagree on the date of the same holiday. And all of it comes down to the fact that the length of the Earth's rotation (day), the duration of one lunar cycle (a lunar month), and time it takes the Earth to complete one orbit around the sun (year) are not even multiples of each other. (Heck, there are even different types of years, but let's not go there). Aren't calendars fun?

Tuesday, April 07, 2009

Can Visual Astronomers still contribute to science?

In today's 365 Days of Astronomy podcast, Mike Simonsen talks about whether visual astronomers (those who use their eyeball, not photography or digital imaging, to make measurements of the brightnesses of stars) can still contribute to modern astronomical research. And the answer is, yes, even in this age of robotic telescopes, all-sky surveys, and computerized cameras, visual observers can still make valuable contributions. If you haven't already listened to the podcast, go listen, and see if you agree. (And, while you are at it, subscribe to the podcast so you can get a daily dose of astronomy through the end of the year.)

Mike covers all of the arguments pretty well, so I have no real points to add. Amateur and semi-professional astronomers contribute in a lot of ways to professional research, from studying nearby stars to studying distant galaxies. There's a lot of important, fundamental work that would not get done without their help, and I think most of us professionals realize the amount and quality of the work this unpaid workforce does for our science.

Monday, April 06, 2009

The Friday: 400 Years of the Telescope

An actor portrays Galileo peering through his telescope Dr. Lawrence Krauss at Kitt Peak
Images courtesy Interstellar Studios (click on the image for larger versions and copyright restrictions)

This Friday (April 10) at 10pm Eastern/Pacific, 9 Central, PBS will air a new high-def documentary called 400 Years of the Telescope, a production by Interstellar Studios created as part of the International Year of Astronomy 2009.

I attended the premier of this documentary at the American Astronomical Society Meeting back in January; you can read about that experience (and my own opinion of the documentary) here. It's worth the time spent to see the story of how the telescope evolved from a military invention, through Galileo, and up to today's precision scientific instruments.

In addition to the PBS special, the documentary has a companion planetarium program that will tour select planetariums throughout the United States, and which will be distributed to planetariums around the world.

There are also companion teaching resources available.

If you can't watch the documentary on Friday or attend a planetarium showing, I suspect that the video will be on sale and/or available via Netflix in the near future.

Update (1:35pm CDT): Oops, title should read "This Friday," not "The Friday." It's the Monday, and the part of my brain that deals with the definite articles in the grammar is obviously still alseep.

Sunday, April 05, 2009

It's Sun Day!

Today is Sun Day, the last full day of the 100 Hours of Astronomy celebration. Since most people can't stay up late tonight for more stargazing,today is a day aimed at (safe) viewing of the sun. So, look to see if you can find a solar telescope set up somewhere near you! If there are no events near you, you can try safely observing the sun yourself. If you are worried about doing so, or if it is cloudy, check out some online images and webcams from solar telescopes and satellites.

I can't overemphasize the need to be safe when observing the sun. Here's a list of some ways to look at the sun safely. Looking at the sun, even briefly, through an unprotected telescope can permanently damage your eyes. On a personal note, my ophthalmologist noted that I have some minor damage on my retinas, probably from unprotected viewing of dozens of sunsets from high altitude observatories. But that doesn't mean you need to be scared; you just need to be careful. Read this old blog post for a personal anecdote of someone who was a little overzealous about safe viewing during a total solar eclipse (about halfway through the story).

Friday, April 03, 2009

100 Hours of Astronomy now and throughout the weekend

With the weekend looming (or already started, depending on where you live), the 100 Hours of Astronomy world-wide astronomy festival is underway. I blogged about many of the events earlier this week, but right now you can watch professional astronomers at observatories around the globe working and sharing discoveries with you, all streaming over the web. Tonight and tomorrow night, there will be sidewalks star parties throughout the world, where you and your family/friends/giant invisible rabbits can go and look through telescopes without cost or obligation. Just click here to find registered star parties near in the U.S.A., or be on the lookout for telescopes near you! (There used to be a nice tool for finding events world-wide at the 100 Hours website that seems to have disappeared. Here's the link anyway, in the hopes that someone will put it back up again soon.)

It looks like several of my links from my earlier blog post are dead; evidently somebody revised the website structure at at the last minute. Not smart, guys!

UPDATE (11:05am CDT): Evidently, the website has been pared down to deal with the large number of visitors. That still doesn't help people find events for tonight, but what do I know? (I always get grumpy when websites run out of bandwidth; this used to happen a lot to NASA during shuttle launches. But if the bandwidth problem occurs during a planned streaming broadcast that the site heavily advertised, then someone didn't do enough contingency planning. I realize that the vast majority of the 100 Hours stuff is planned by volunteers who don't have a lot of time for this, and I realize that the company doing the streaming, ustream, has had some technical glitches in the past day, too. Even so, it still makes me grumpy. Oh well, too late now.)

Thursday, April 02, 2009

Texas Astronomy Under Review

This week, we astronomers at the University of Texas have found ourselves in an unusual position. Whereas we are used to sitting at the base of a telescope, taking magnified pictures of the heavens, this week we were under a microscope, being examined by others. No, we weren't the center of an outbreak of some alien disease. We were being reviewed.

Every ten or fifteen years or so, we (and most other astronomy departments, at staggered times) bring in a panel of astronomers to examine every aspect of our department and observatory. Our turn was this week, as four astronomers from across the country flew into Austin.

Our review began months ago. At the start of the academic year in September, the department put together an internal report. All of us submitted our resumes, various committees reported on the teaching programs, research programs, outreach programs, our goals for the future, our opinions of the strengths and weaknesses of the department, and so on. The department leadership nominated the members of the committee, and their visit to our department was all planned.

This week, the committee arrived on campus. They spoke with the different research groups, academic groups, department staff, and even the dean of the college. Two of the committee flew out to McDonald Observatory for a quick overnight visit, where they toured the telescopes and had numerous talks with the staff and engineers.

This morning, the committee met with the department for the last time, and they gave us their opinion of where the department stands. And we fared pretty well. We've got a lot of things going for us, and a lot of things to work on. (And no, I'm not going to go into those today. Maybe some other day, once reports are finalized and filed and read and considered. Or maybe not.) But we are all grateful for the large amount of time and energy the external committee gave for this process, and we are all happy that the process is just about over.

Wednesday, April 01, 2009

The Great Madoff Telescope

The Giant Madoff Telescope
Artist's conception of the Great Madoff Telescope, soon to be built in the Egyptian desert.

Astronomers of the University of Texas State at Junction and the University of Giza announced today that they will be constructing the world's largest telescope in the Egyptian desert using a novel, pyramidal design.

The Great Madoff Telescope, or GMT, is named after its primary designer and largest financial donor. With a minimum aperture of 139 meters (the size of the Great Pyramid of Giza), this telescope will be the largest telescope ever constructed.

"The most striking feature of this telescope, next to its size, is its inverted pyramidal shape," said Olaf Pilor, professor of astronomy at UTSJ. The Giant Madoff Telescope's design is based on a novel scheme by engineer Chuck Ponzi. Mirrored panels on each level of the pyramid reflect light down to the next level, which in return reflect it down to the following level, and so on, until the light reaches the apex of the pyramid, at which point it is funneled into the Giant Madoff Telescope Control Center.

Once in the control center, located in a sphinx-shaped building carved to look like the telescope's primary malefactor benefactor, the light is re-directed into numerous rooms, nooks and crannies. At this point, astronomers hope to be able to examine the light using sensitive instruments known as regulators. "The final design of these instruments has yet to be decided," intones Pilor. "Mr. Madoff has not yet provided final details on the layout of the instrument room. However, we trust his word that everything will be ready on time."

One of the most daunting aspects of the Giant Madoff Telescope project will be the construction phase. "We have to start with the tip of the pyramid," says Pilor. "We then add the mirror banks, one level at a time. With each additional level, more light will be funneled to the GMT Control Center. In short, the more we build, the more we get."

When asked how many levels the completed telescope will require, Pilor demurred. "We'll see," he said. "As long as each new level can supply the previous levels with sufficient light, I don't see any real limit to the eventual size of the telescope."

The Giant Madoff Telescope represents the second ambitious astronomical undertaking at the University of Texas State at Junction. Their first endeavour, a solar telescope designed by Princeton physicist Freeman Dyson, will provide astronomers their first ever simultaneous mapping of the entire sun, as well as provide roughly 400 Yottawatts of energy for the Pedernales Electric Coop of central Texas.