Dan’s latest: Yet Another Planetarium Simulation

Great news! Dan Schroeder, the physics professor whom some of you will remember from his excellent reviews of iPhone astronomy apps, has written his own astronomy applet. Give it a look.

Why write another astronomy program? Here’s Dan’s answer.

To be useful to most of my students, a simulation program has to be (a) free; (b) delivered through a web browser, with nothing to download or install; (c) easy for beginners to understand; and (d) convenient for showing the motions of the stars and other objects with respect to earth’s horizon.

It’s a lot of fun to play with, and I like how Dan notes that his UI was partially inspired by H.A. Rey’s stargazing books, of which I too was, and remain, a loyal fan.

Dan’s iPhone Astronomy

Here’s the setup for a joke: once there was a mathematician, a physicist, and an engineer, and… Oh, wait, that’s not the setup for a joke. That’s a description of my house in grad school. Okay, it was actually a trailer, not a house, but that’s not important. For the purposes of today’s story, what you need to know is that I was the engineer in the trio, and Dan was the physicist. Dan is now on the faculty at Weber State in Ogden, Utah. He has a blog that I enjoy reading, and as an iPhone owner I was especially pleased to come across his very thorough review of iPhone star charting applications.

I always liked looking over Dan’s shoulder when he was evaluating products he was considering buying (camera lenses, star charts, baking supplies), because Dan is the most thorough evaluator I know. Go look at his star chart reviews and you’ll see what I mean. He’s a one-man Consumer Reports! Read what he has to say and buy one of the recommended apps. It’s a good thing to know the stars in your neighborhood.

Thanks Dan!

Galaxy on the rise

Once on a camping trip in Utah, I took a picture of our group late at night. I had a tripod and used a long exposure, but not being a very skilled photographer, I wasn’t sure how it was going to turn out. When the pictures came back from the lab, I was in for a surprise (historical footnote: in ancient times, photographs were “developed” at remote mountaintop “laboratories” and returned to you on the backs of fast-trotting donkeys). I couldn’t find my night-time snapshot. It was a while before I realized what looked like a mid-day shot was actually taken at midnight. The sky was bright blue and the colors were vibrant. Only the tiny traces of stars in the sky and our blurry faces gave it away. It was hard to believe my little camera could see such a different world.

On Kevin Kelly’s sprawling site I came across this lovely time-lapse animation taken at a star party in Texas. Amazingly, it was taken with an SLR camera on tripod. Put on your slow eyes and watch the earth turn.


Galactic Center of Milky Way Rises over Texas Star Party from William Castleman on Vimeo.

I’m familiar with what the Milky Way looks like in dark skies, so I was watching this video thinking “It’s going to be subtle… is that it? No… is THAT it? No.” But that camera has better eyes than you or I do. When the galaxy comes up, trust me, it’s not subtle.

Galileo’s telescope

It’s been a big year for anniversaries. First we have Abraham Lincoln and Charles Darwin blowing out 200 candles apiece (were they jealous of each other?), and now comes a Galileo event at twice that span: 400 years. When you put it that way, it’s interesting to consider that Darwin gets you halfway to Galileo. Quick question: if two Darwins buys a Galileo, what can you buy with two Galileos (800 years)? Answer: Cambridge University, which was founded in 1209. So it goes.

But back to Galileo. In fairness, we are talking not about his birth year (1564), but the first year in which he turned his famous telescope upon the heavens. A curious historical footnote is that Galileo did not invent the telescope, but he does seem to have been the first to think to point it straight up. In honor of the events of 1609, this year is to be an International Year of Astronomy. Last weekend witnessed the 100 Hours of Astronomy celebration. Visit their web site to see some fun short videos from observatories around the world in Around the World in 80 Telescopes.

But what about Galileo’s original telescope? You can still find it (or one of its early siblings anyway) at the Istituto e Museo di Storia della Scienza in Florence. I’ve been there, and let me tell you it is worth the visit.

As you enter the museum, you see part of an enormous marble dial for a barometer and thermometer that used to sit in the Loggia dei Lanzi in the famous Piazza della Signoria. But, this being Florence, public displays of science gave way to public displays of art, and so the instrument was banished to the museum. On the second floor you can find not only Galileo’s old telescopes, but also, bizarrely, his old finger. It is, in fact, his middle finger, and although Galileo was pardoned by Pope John Paul II in 1992, I would have to guess that it still points at Rome.

The sky in motion

Check out these beautiful time lapse movies of the nighttime sky: The Sky in Motion – Movies – Digital Images of the Sky. The quality of the photography is superb, so the movies are like butter. Like dark starry butter smeared all over the sky. Okay, there’s no such thing as dark starry butter, but if there were, it would be like that.

Be sure and click on the “playlist” link hiding on the left side of the page. Then you’ll be able to see some other movies like drowning in the clouds.

(Thanks Steve Crandall for the link)

Pictures of the Sun

It’s fun to look at pictures of planets taken by our robotic eyeball extenders. We get to see things that are too darn far away to see with even the biggest earthbound telescope.

But there’s another kind of treat when we look at our own sun with new eyes from here on earth. We’re used to seeing marvelous detail in the moon’s changeless cratered face, but the sun is just a blinding fireball to our eyes.

When I look at a planet, I think “That’s a place.” I can imagine flying over it, or even stepping out of my little tin spaceship onto its surface. But the sun is always just the sun. Not really a place, just a white hole in the sky. My imaginary spaceship never goes there.

New telescopes (and a few space probes) are changing that. The featureless sun is really a charismatic world of curdling fire, boiling magnetic storms, and vast billowing exhalations of solar steam.

These pictures (from the Boston Globe’s Big Picture series) prove that the sun is a place jammed with personality: The Sun – The Big Picture. And if you want to know why they call it “solar wind”, be sure and look at the animation where a strong gust from the sun whips the tail off a comet

Sight-seeing on Mars

Yowza! Check out this panoramic landscape from Mars.


It’s from a place called Hebes Chasma. What you’re looking at is a plateau in the middle of a canyon 8000 meters deep. That is to say, this thing would make a dandy bathtub for Mount Everest (8848 m). Mind you, that mountain could use a good scrubbing, what with all the tramping and the digging and all those filthy climbers.

It’s too bad we don’t have Google Maps to show us the neighborhood on Mars. Oh, I almost forgot that we live in the future! Of course we have automatic mechanical Mars Maps!

The ESA site that describes these pictures is also worth a visit. I really like living in the future.

(via Riding with Robots)

Google Sky and Comet Holmes

The latest version of Google Earth now has a projection of the sky built into called, fittingly, Google Sky. It’s a natural extension. We’ve got lots of pictures of the starry sky, so why not stick them all together using the Google Earth glue that already exists. But when I tried it for the first time, I was underwhelmed. If you want to learn your way around the stars, the freeware package Stellarium does a much better job. But I soon realized that’s not exactly the point. Google Sky can act as a focal point for aggregating shared data about the heavens just as its Earthbound sibling does for terrestrial data like storm tracks and botanical surveys. See for example this Popular Science note: Google Sky a Hit With Astronomers. Incidentally, there’s a similar professional sky-watching tool called WikiSky, but it doesn’t have a lot of the slickness of Google Sky.


Anyway, I figured that somebody would have entered special data about where to find Comet Holmes in Google Sky. They had. I was able to follow a link that placed this little indicator of the comet’s location on my screen. I really liked the fact that the interface has this holdover from the Earth-facing side: directions to and from the comet. I’d like to see those directions.

Take exit 9 to merge onto I-84 W toward US-20/Sturbridge/Hartford (41.7 mi). Take exit 57 on the left to merge onto CT-15 S toward I-91 S/NY City (2.6 mi). Turn straight up and head directly toward Mirfak/Alpha Persei (25.43 million mi). Turn right onto Holmes St (1.3 mi).

[originally spotted on O’Reilly Radar]

Earth, Moon, and Sun

Did you know that the Japanese have a space ship orbiting the Moon right now? Known variously as SELENE or Kaguya, it is, as we speak, floating around the Moon, taking gorgeous high definition video. So much of our mental imagery of the lunar landscape is based on Apollo video from the early 1970s, grainy snowy pictures from another world. But video technology, happily, has gotten much much better in the intervening 25 years. And we all get to profit from Japan’s exploration.

This particular video is only YouTube quality, but it’s still mesmerizing. A tiny blue and white Earth rises over the lunar horizon at about a minute and a half into it. You may be impatient to get to the “good part”, but I beg you to press play and let it go at its own speed. There’s no soundtrack, there’s no artificial speed-up. It’s just what you would see out your window, silent as death, endlessly rolling. When our little home comes quietly calling, it is lovely to behold.

Stick around for the whole show, because at around six minutes, you see the Earth (larger this time) sink into the darkness astern your moonship.

When you’ve tired of Earth and Moon, follow this APOD link to look at the video of a massive solar flare. It makes our pale planet seem all the more fragile. I look at these astronomical videos and I have to keep telling myself: these are real. There are no special effects involved. No special effects beyond, you know, flinging delicate camera equipment into the frozen nameless void and whispering the pictures back to our breakfast tables. I guess that’s special.

Comet Holmes is easy to see

I had read that Comet Holmes had brightened dramatically, but I am suspicious of the word “dramatic” when used by astronomers. The events they describe are undoubtedly dramatic, but the images they describe are often tiny smudges even when observed through a big fancy-pants telescope. So I was pleased tonight when I finally had a good chance to look for the comet (having just been lashed by the coattails of Hurricane Noel), and wow! it just about hit me in the eye.

If you haven’t seen it already, I am here to tell you that it’s, well… it’s a smudge. But it’s pretty dramatic as smudges go: a big fuzzy ball and perfectly visible to the naked eye in a big metropolitan area. If you want to find it, Sky and Telescope has a growing site about it, as well as a finder map to help you locate it. If you already know where Mr. Perseus lives, just look up and you can’t miss the tennis ball that’s falling past his right shoulder.