NASA has just released more images of Mercury as seen by the MESSENGER spacecraft, and they’re pretty cool:

This first one is something of a repeat, showing the same region as the picture they released yesterday, but now it’s in color! Mercury is not exactly the most beautifully hued planet, but it does have some color to it. This composite was taken in the infrared (shown red in the image), red (shown as green in the image) and blue (shown as blue), and has a maximum resolution of about 2.7 kilometers (1.6 miles) per pixel. While most of the surface looks gray, look again: some of the craters do show subtle color variations. This is most likely due to the material excavated on impact — composition, particle size, and other factors change the way these features reflect light. This image only uses three colors, but the wide angle camera has eight 11 filters, which will allow planetary scientists to map the planet very effectively and learn about the composition and history of the surface.
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The MESSENGER spacecraft settled into orbit around Mercury earlier this month, and engineers have been busy making sure it’s functioning well. Now, the first pictures are coming in from the solar system’s innermost world, and as expected, wow!

Cooool! Or rather, hot. I mean, duh, it’s Mercury. [Click to ensmallestplanetate.]

The picture is dominated by the crater Debussy (named after the composer, who wrote "Clair de Lune", apropos of nothing, I suppose^*), an impact crater about 80 kilometers (50 miles) across. It’s a rayed crater, with plumes of ejecta leaving those long, linear features across the planet.

This image is the first ever returned from a spacecraft orbiting Mercury, but MESSENGER has already taken hundreds more, and thousands are planned during this commissioning phase (when the various instruments and spacecraft are checked out). The real science observations begin April 4.

Tomorrow, NASA will have a press conference and more images. I’ll have more info and more amazing pictures from Mercury to show you then!

Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

^* Oh, duh. After posting this article I realized he also wrote "Trois Scènes au Crépuscule". Why is that appropriate? Because Debussy is a rayed crater.

Just a quick note to y’all, since I’m in the middle of about eight things all demanding my full attention: the MESSENGER spacecraft will enter orbit around Mercury tonight at 9:00 p.m. EDT, after a tortuous 7-year journey. Once safely circling the planet, engineers will be focusing on making sure the probe is safe and sound, so it’ll be a while (days) before we start getting images.

I’m quite sure my pal Emily Lakdawalla will be poised for attack on every tidbit of news that comes in, so follow her on Twitter and on her blog at the Planetary Society.

If you have good eyes and a flat horizon, then you can spot Jupiter and Mercury this week as they pass each other in the night twilight.

As the planets orbit the Sun, we see their position in the sky change. Right now, Jupiter is (apparently) getting closer to the Sun every day, setting in the west a bit earlier every night. Mercury, on the other hand, is apparently moving away from the Sun, getting higher off the horizon with each passing day. On the evenings of March 14 and 15th the two planets will pass each other, with a closest approach of roughly 2° — about 4 times the width of the full Moon. That’s actually pretty close, and they’ll make a pretty pair in the west just after sunset.

And I do mean just. When the Sun sets, the two planets will be only about 10° off the horizon, where the sky will still be bright from twilight. Even though Jupiter will be shining at a magnitude of -2 (making it the fourth brightest natural object in the sky after the Sun, Moon, and Venus), and Mercury at -1, they might be a bit tough to see depending on your local conditions. Binoculars might help, but make sure the Sun is gone before scanning for the planets!

The image above is a rendering using software of what the scene might look like for you. This shows the view just after sunset, with the pair labeled. Funny, too: when I made this, I saw just how close the Sun was to setting due west. That means spring is almost here! The Sun sets due west on the equinox, which is March 20 this year.

Anyway, if you get the chance to see the two planets, take it! Jupiter will be a morning object after this, and won’t be visible unless you get up at the wee hours. Mercury moves rapidly day after day compared to other objects, and never gets very high off the horizon. Most people have never seen it, so you should grab this opportunity… after all, it’s not often the solar system’s most extreme planets flirt this way.

On March 17, just a month from now, NASA’s MESSENGER probe is scheduled to enter orbit around Mercury, the smallest planet in the solar system. No other mission from Earth has ever done this, and for the first time we’ll get high-resolution maps of the entire globe.

On its way down, the spacecraft was commanded to turn around and look outward, toward space. It took a series of images of what it saw… this astonishing family portrait of the solar system:

Click it to ensolarsystemate it and see it in more detail. When you do you’ll see the five classical planets in our system, as well as the Earth and Moon. Uranus and Neptune are there, but too faint to see, unfortunately, but still, this is an interesting picture. In November 2010, when these pictures were taken, Mercury was still nothing more than a dot. In fact, all the planets as barely more than dots, a reminder that this probe is well away from home and nowhere near any solid ground.

I like very much the images of Venus and the Earth. Venus is technically the closest planet to MESSENGER besides Mercury, though it depends on where the planets are in their orbits. It’s extremely bright as seen from the spacecraft, since MESSENGER is inside the orbit of Venus: the planet is therefore close to being full (like the full Moon) and reflects a lot of light back to the cameras.

And the Earth is accompanied by the Moon! That always amazed me. I’m so used to seeing pictures of just the Earth from space that it’s easy to forget that the Moon travels along with us. An important reminder in this picture is just how far the Moon is from us; 400,000 km is over 100 times the Moon’s size, so it appears to be a dot located well away from its home planet. If you wanted to make a scale model of it, a good way would be to use a golf ball to be Earth, and a marble located a meter away to be the Moon. That really brings home — ironically! — how small and distant our Moon is.

If you look to Jupiter you can see it has a couple of moons near it as well. The four moons spotted by Galileo 400 years ago are pretty big; Ganymede is actually about the same size as Mercury itself! Were Jupiter not there, Ganymede might be considered a planet on its own.

I smiled when I saw the section of the picture between Jupiter and Mars — that fuzzy glow is the Milky Way itself! The split down the middle is a dead giveaway; that’s caused by dust located in the disk of our galaxy. That section of the sky looks toward the center of our galaxy in the direction of the constellations Scorpius and Sagittarius.

I mention that last part on purpose. (more…)

Regular readers may know me as the beloved online blogger for Discover Magazine, but I also sometimes write longer articles for the print version as well.

Last summer, I wrote a piece on the search for small solar system objects that might, theoretically, circle the Sun inside Mercury’s orbit. Called vulcanoids, they are extremely difficult to observe, which is why it’s still not certain if they exist or not (I wrote a brief post about this back in 2008). Two astronomers (and friends of mine), Dan Durda and Alan Stern, are hot on the trail of the purported possible planetesimals; I talked to them about their chase and the history of the search for these hot little objects.

Until now, the article was only available in the print magazine or to online subscribers, but now my brilliant prose is open to the public. Seriously, this is a pretty cool topic, and one that most people don’t know about. The region between the Sun and Mercury is closer to the Earth than the main asteroid belt, yet we know much less about it. Read the article and find out why.

Over the next few days, get yourself outside at sunset and look west. As the sky darkens, Venus will be obvious and easy to spot above the horizon, a brilliant beacon hovering in the sky. But for a few days, the elusive Mercury will also be popping in for a visit!

Mercury orbits much closer to the Sun than Earth does, and so from our vantage point never seems to stray far from our nearest star. It’s always lurking in the twilight, and most people can go their whole lives without seeing it. It’s rumored (though by no means established fact) that Copernicus himself never saw Mercury. But this week will provide you with an excellent chance to spot it. It will stay near Venus for several days, and with no other bright stars nearby it will be fairly easy to pick out.

Both Mercury and Venus move faster in their orbits than Earth does, so if you go out every night you’ll see them change positions slightly in the sky. From our perspective, Venus is on the far side of the Sun, and Mercury to the side. After about April 10, Mercury will start to fade rapidly, so get out there and take a look! More info and diagrams to help you spot the planetary duo can be found at the Sky and Telescope website.

And I’ll add that if you have a digital camera, try to get some photos! The planets are bright enough to show up in images easily, and if you get an interesting foreground object (a tree, a bridge, etc.) you can get some very nice shots.