Emily Lakdawalla — scientist, blogger, and all around cool chick — has just posted a totally awesome scale diagram comparing every asteroid and comet visited by spacecraft. It features pictures of all the rocks, each of which she has carefully resized so you can see just how big they are relative to each other:
Whoa. Look how big Lutetia, just visited by Rosetta, is compared to everything else! And yet, at 130 km across, it’s a dot compared to our Moon. In fact, you could smash together all the known asteroids in the main belt between Mars and Jupiter and they’d be far smaller than our rocky satellite.
Still, small doesn’t mean "uninteresting". These rocks in Emily’s diagram are all fascinating beasts, and the more we learn about them the more compelling they become. And there’s more to come, with the Dawn mission about to see the big asteroids Vesta and Ceres up close… and go read Emily’s blog about this to see how they’d fit on the diagram (hint, they don’t, and by a long shot). You’ll also find a much larger version of the diagram there, and you really, really should look at it. Wow.
The European space probe Rosetta passed about 3000 km from the asteroid Lutetia on Saturday, July 10, 2010, and it sent back incredible closeup images of the rock. Check ’em out below!
At 15:45 UTC tomorrow, July 10, the European Space Agency probe Rosetta will fly to within 3200 km (2000 miles) of the asteroid 21 Lutetia. This close pass will reveal, for the first time, the shape and details of this roughly 100-km-diameter rock.
You can watch this event live as it happens; ESA is streaming the event. Around 01:00 UTC they’ll start presenting the images, too. Below is an embedded feed that will go live once the actual stream starts.
We humans have been busy lately… there are a lot of spacecraft buzzing around the solar system. Sure, you’ve heard of Cassini, and the Mars probes, but there are two very interesting spacecraft making two very interesting encounters in the next few weeks.
1) On June 27, NASA’s Deep Impact spacecraft — which sent a chunk of copper smashing into a comet back in 2005, and which has now been repurposed for planetary science — will swing by the Earth, using our planet’s gravity to change its direction and speed. DI will pass at a distance of just 37,000 km (23,000 miles)! That’s around the same height above the surface as geosynchronous (i.e. weather and communication) satellites. This maneuver will send the little spacecraft on its way to an encounter with the comet Hartley 2 in November.
2) The European Space Agency’s amazing Rosetta spacecraft will fly by the asteroid 21 Lutetia on July 10. The asteroid is about 95 km across (60 miles), and the flyby distance will be about 3200 km (2000 miles). That’s pretty close, certainly near enough to provide some nice images of the rock. In 2008, Rosetta passed the smaller asteroid 2867 Steins and returned nice images, and in 2009 swung by the Earth, sending back an image so heart-achingly beautiful I chose it as one of my Top Ten images of the year.
Rosetta’s primary mission is taking it to the comet 67P/Churyumov-Gerasimenko, where it will drop an actual honest-to-FSM lander on the comet’s surface! This is a tremendously exciting mission, and I can’t wait to see what new wonders it will send us.
Tip o’ the Whipple Shield to Emily Lakdawalla for the Rosetta news.
Not that deciding what pictures to use in 2006, 2007, or 2008 was all that easy! But astronomy is such a beautiful science. Of course it has scientific appeal: the biggest questions fall squarely into its lap. Where did this all begin? How will it end? How did we get here? People used to look to the stars asking those questions, and coincidentally, for the most part, that’s where the answers lie. And we’ll be asking them for a long time to come.
But astronomy is so visually appealing as well! Colorful stars, wispy, ethereal nebulae, galactic vistas sprawling out across our telescopes… it’s art no matter how you look at it. And our techniques for viewing the heavens gets better every year; our telescopes get bigger, our cameras more sensitive, and our robotic probes visit distant realms, getting close-up shots that remind us that these are not just planets and moons; they’re worlds.
So every year the flood of imagery takes longer to sort through, and far longer to choose from. And the choices were really tough! This year leans a bit more toward planetary images than usual, but that’s not surprising given how many spacecraft we have out there these days.
I don’t pick all these images for their sheer beauty; I consider what they mean, what we’ve learned from them, and their impact as well. But have no doubts that they are all magnificent examples of the intersection of art and science. At the bottom of each post is a link to the original source and to my original post on the topic, if there is one. If you disagree with my picks, or think I’ve missed something, put a link in the comments! All the pictures have descriptions, and are clickable to bring you to (in most cases) much higher resolution version. So embiggen away!
And welcome to my annual Top Ten Astronomy Pictures post. Enjoy.
The European Space Agency probe Rosetta is on its way to comet 67/P Churyumov-Gerasimenko (by way of asteroid 21 Lutetia next July), where it will arrive in May of 2014. It will be dropping a lander — the first ever attempted on a comet — and our knowledge of these fuzzy visitors will increase enormously.
But getting there is tough, and involves swinging by the Earth three times and Mars once. The final gravity assist will occur on November 13, with closest approach at 08:45 CET (over, roughly, the island of Java) when it’ll be moving past us at 13.3 km/sec (almost 30,000 mph). While it’s passing us by it will observe both the Earth and Moon, doing as much science as it can before heading out into deep space. Specifically, it will add its sensors to those already studying water on the Moon, as well as aurorae on Earth.
You can follow the action on the Rosetta blog. In fact, just the other day they posted this awesome shot of the Moon from Rosetta:
That was taken form a distance of 4.3 million kilometers (2.5 million miles), ten times the distance of the Moon from the Earth. The images as it gets closer will be even cooler.
So stay tuned! This is a very exciting mission, especially next year when it passes Lutetia! I can never see enough closeup pictures of asteroids.
Spacecraft image credit: ESA, image by AOES Medialab
Phil Plait, the creator of Bad Astronomy, is an astronomer, lecturer, and author. After ten years working on Hubble Space Telescope and six more working on astronomy education, he struck out on his own as a writer. He's written two books, dozens of magazine articles, and 12 bazillion blog articles. He is a skeptic and fights the abuse of science, but his true love is praising the wonders of real science.
The original BA site (with the Moon Hoax debunking, movie reviews, and all that) can be found here.
Contact me: The Bad Astronomer "at" gmail "dot" com
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2) The European Space Agency’s amazing Rosetta spacecraft 
