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.

Two faces of a moon

“Japetus is unique in the Solar System—you know this already, of course, but like all the astronomers of the last three hundred years, you’ve probably given it little thought. So let me remind you that Cassini—who discovered Japetus in 1671—also observed that it was six times brighter on one side of its orbit than the other.

“This is an extraordinary ratio, and there has never been a satisfactory explanation for it. Japetus is so small – about eight hundred miles in diameter—that even in the lunar telescopes its disk is barely visible. But there seems to be a brilliant, curiously symmetrical spot on one face, and this may be connected with TMA-1. I sometimes think that Japetus has been flashing at us like a cosmic heliograph for three hundred years, and we’ve been too stupid to understand its message.”

Arthur C. Clarke gave these words to his fictitious astronomer Heywood Floyd near the climax of his book 2001: A Space Odyssey. Like a lot of people, I read those words years ago and thought to myself: what is the dang deal with Japetus? Clarke wasn’t making up the part about the two-faced nature of Iapetus (as it is more commonly called), an oddball Saturnian moon.

The two-toned satellite is still mysterious, but now we have some quality snapshots from the visiting Cassini spacecraft. And, hoo boy! they do not disappoint. I find this APOD picture astounding: The Strange Trailing Side of Saturn’s Iapetus. Great Clarke! Look in the sky! It’s a cosmic snowball rolled in dirt… it’s a sugar-frosted chocolate space truffle… it’s… it’s a much better investment than the International Space Station. You know what we need? I’ll tell you what we need: more space robots with cameras and fewer accident-prone gold-plated Tang-sucking astro-cosmo-taikonauts.

All the pictures from the Hubble Telescope

Many people don’t fully realize that the appeal of amateur astronomy is cerebral rather than a visual. An expensive telescope can afford you some breathtaking views of the moon as well as a nifty view of Jupiter and its satellites. Saturn is a minor thrill, and a few of the larger nebulae also make for fun viewing. But at that point, as far as pure visual spectacle goes, you’re pretty much done. The moon will look the same the next time it’s full. It doesn’t change much. The Orion nebula doesn’t change at all. And it’s a pain in the ass to move that big telescope back into the yard. This is why, on a typical night, so many telescopes gather dust rather than starlight.

If the essential notion of it doesn’t thrill you, then observing variable stars is about the most boring thing imaginable. An enthusiast will get very exercised about the occultation of Regulus by the dark limb of the passing moon. But what are we really talking about here? The star is there, and then it winks out of sight. I can see both sides of this argument. On the one hand, what a majestic event! The inexorable interposition of massive heavenly bodies made plain to our tiny Earthbound eyebones. Oh, the grandeur! The hand of God is surely there. On the other hand: big freaking deal. I’m cold. Why did I stay up for this?

If, however, you had the Hubble Space Telescope at your command, it would be a different story. For a machine like that, the visual thrills never stop. So I was really happy to find a site that does a good job cataloguing all the magnificent pictures taken by Hubble over the years: HubbleSite.

I’ve always found the Hourglass Nebula MyCn18 to be particularly haunting. I’d be willing to bet that freely available pictures like this will do more to recruit more future astronomers than backyard telescopes ever did.

A year of full moons on Flickr

Full Moons over Flickr
Happy New Year! Not only is it a new year… a quick look out the window or at the Sky Clock reveals that there is a full moon in the sky tonight. Of course, you might not know that if you were locked in a windowless room. Suppose, for example, you were trapped in a room with nothing but a pen knife, a box of paper clips, and access to all the pictures on Flickr. Could you work out when the moon is full? If you are as clever as Jim Bumgardner you wouldn’t have any trouble at all. But since he’s the author of Flickr Hacks, I guess that’s only fair.

Bumgardner took pictures on Flickr that are tagged “full moon” and plotted them according to when they were taken (Flickr knows that because digital cameras encode it in the image). The result is this: A year of full moons. There’s another lovely image where he uses a similar approach to show the seasonal variation in sunset time: A year of sunsets.

This is an example of the informational residue that gets smeared absolutely everywhere on the web. You can learn the most fascinating things these days if you know how to scrape up the data slime. For instance, from the sunset picture mentioned above we can work out the average latitude of Flickr customers. Google Trends can also give you a sense of when the moon is full simply by watching what people search for. Not surprisingly, werewolf searches are somewhat correlated. [Bumgardner’s photos via the Kircher Society]

The earliest sunset

The earliest sunset
My part of the world was gray, dreary, dark, cold, and wet today. But it had one thing going for it, one very big thing: the sun set this afternoon a few seconds later than it did the day before. Ordinarily I wouldn’t bother splitting hairs over astronomical minutiae, but it helps get me through December to recall that, although the total number of daylight hours will keep shrinking until the 21st or so, the sunsets are now occurring later and later every day and so will continue until late June. Mmmmm… June. Why does the earliest sunset not match the shortest day? Here is a helpful diagram with ellipses and annotations to explain it.

Confusing ellipses

I hope that’s clear. If I work at it, I can understand how it all works for an hour or so, but then it fades.