Thierry Legault is no stranger to this blog (see Related Posts below or search the blog for his stuff); his astrophotos are always amazing. Always. And he just sent me a link to a new batch that are jaw-dropping: very high-resolution images of the Moon, Mercury, and even Uranus. As an example, here is a shot he got of the giant crater Clavius on the Moon:
I shrank that image way down to fit the blog; click it to monolithenate. The detail is astonishing. There are lots more shots of the Moon like that on his site; and you most certainly want to click the links to Uranus and Mercury above. You can see details on both planets (the surface for Mercury, and cloud tops for Uranus)!
I always say that astronomy is much more than just pretty pictures, but sometimes, when the pictures are as pretty as this, astronomy is quite simply art.
[One gold star to anyone who can identify the title of this post without looking it up.]
Image credit: Thierry Legault
– Interloper of the Venus transit
– China’s space lab has a spot in the Sun
– Doomed ROSAT captured in video
– Atlantis, one last time in the Sun
– SERIOUSLY jaw-dropping pictures of Endeavour and the ISS!
– INSANELY awesome solar eclipse picture
One of the enduring mysteries of our solar system is why Uranus is tilted over on its side. If you measure the angle of a planet’s rotation axis (the location of its north pole) compared to the plane of its orbit, you find that all the planets in the solar system are tipped. Jupiter is only 3°, but Earth is at a healthy 23° angle; Mars is too. Venus is tipped so far over it’s essentially upside-down (we know this because it spins the wrong way).
Uranus, weirdly, is at 98°, like it’s rolling around the outer solar system on its side. The best guess is that it got hit hard by something planet-sized long ago, knocking it over (though there are other, more speculative, ideas). The problem with that is that its moons and rings all orbit around its equator, meaning their orbital planes are tipped as well. It’s hard to see how that might have happened, even if you assume the moons formed in that collision (as, apparently, our Moon formed in an ancient grazing impact with Earth by a Mars-sized body).
Well, a team of astronomers have come up with a new idea: maybe Uranus wasn’t hit by one big object. Maybe it was hit by two smaller ones.
So you’ve probably heard that tonight, Jupiter is as close to Earth as it’ll get in many years. While this is true, and pretty cool — and I certainly don’t want to damp enthusiasm for anyone wanting to go outside and see it! — I want to make sure you understand what this means.
First of all, this whole thing is happening because Jupiter is at opposition: that is, it’s directly opposite the Sun in the sky. A better way to think of this is that the Earth is passing very nearly directly between the Sun and Jupiter, so from the Earth we see them on opposite sides of the sky. At this point, the Earth is as close to Jupiter as it can get for that particular orbit. Both Earth’s and Jupiter’s orbits are slightly elliptical, so sometimes Jupiter gets a bit closer to us at opposition than other times; this year is the best in decades. It’s about 590 million km (355 million miles) away. That’s still a pretty long way!
But Jupiter is a big planet, 140,000 km (86,000 miles) across, almost 11 times wider than the Earth! It’s also a whitish color, so it reflects a lot of sunlight. Its size, reflectivity, and close distance together make it a very bright object in the sky. If you go outside any time after sunset tonight you’ll see it in the east, a luminous beacon glowing brilliantly.
However, some people have been saying that tonight is the best night to see it, and we won’t get a chance to see it like this again for years. Shades of the Mars Hoax! In reality, it doesn’t matter if you go out tonight, or wait a few days. While technically Jupiter is closest right now, it’s not like it’ll be a lot farther away tomorrow night. Here’s why.
If you’re an early riser in the mid-northern latitudes of our planet (and statistically speaking, the odds are good for the latter part), then there’s a comet you might want to check out.
Comet McNaught (C/2009 R1) is currently moving rapidly across the northern sky, and it’s just on the edge of being bright enough to see with your unaided eye. Over the next few days it may even get bright enough to see easily in dark skies.
This picture, taken by Ernesto Guido and Giovanni Sostero, shows the comet and its long tail. It’s a multiple exposure centered on the comet, which is why you see several star images for each star. You won’t get a view this nice (probably) with binoculars, but you should be able to spot the tail.
The CometChasing website provides a helpful map of the comet’s location over the next few days. On June 21 it’s pretty close to the bright star Capella (one of the brightest in the sky) but it’s not known how bright the comet will be by then. Also, McNaught reaches perihelion (closest point in its orbit to the Sun) on July 2/3, so it’ll be tough to see in a few weeks (though probably brighter; as they gets closer to the Sun most comets get much brighter, but their proximity to the Sun makes them very difficult to spot). With comets it’s always good to get them while the getting’s good. Go look now!
You can find more info on the Cometography site, a spectacular picture on APOD, and an interesting animated GIF showing the motion of the comet, too.
As a bonus for early risers, Jupiter and Uranus will have a series of close approaches to each other in the sky, so you can check that out as well.
My pal Amanda Bauer — aka Astropixie — has been posting a great series of short videos called Sixty Symbols, where scientists discuss the meanings of a given symbol in science, and the story behind them. In the latest, she tackles the pronunciation of the planet name Uranus — the name is Greek, so I think the title of this post is correct — but the video she made has lots of info on the planet, and I thoroughly enjoyed watching it.
Related post (and to pre-empt any Futurama jokes):
Yes, yes, rings around Uranus, haha
Man, is that way out in the black. The probe is now closer to the orbit of Uranus than it is to Saturn, though both planets are over a billion kilometers away from New Horizons right now.
The solar system is frakkin’ BIG (if I may mix my colorful scifi metaphors). If you’re still not sure just how roomy things are out there, even at its current speed of 16.5 km/sec (10 miles/sec) — fast enough to cross the entire United States in five minutes — New Horizons won’t pass the orbit of Uranus until March 18, 2011, more than a year from now. Neptune’s orbit isn’t until August 24, 2014.
One thing to notice: from this point of view, planets revolve around the Sun in a counterclockwise fashion. Given the position of Pluto, you can see the two are heading for a close encounter soon. Well, for a sufficiently broad definition of "soon": July 14, 2015.
Space is big.
I hate to make the obvious jokes, so I’ll simply say I was on this week’s Skeptic’s Guide to the Universe talking about methane on Mars and the tilt of Uranus. I’m glad they invited me on; I hadn’t heard of either of these stories until Steve Novella alerted me to them before we did the interview.
Basically, a new hypothesis has come out that the large tilt of Uranus (98°) is not from a collision, but instead had its natural tilt reinforced by a large moon that has since been ejected. Also, scientists tested the idea that the methane seen to change on Mars with the seasons might be from meteorites, and find that they don’t supply nearly enough to explain the observations. We also talk JREF, solar power, the Norway lights, and the usual nonsense. I just finished listening to the whole episode, and thought it was pretty good despite me being on it, so go give it a listen!