12 October, 2008

Sunday Sensational Science

Touring the cosmos with Phil Plait.

Astronomy is bad. Like, awesome bad. And Phil Plait is the Bad Astronomer.

Very few popularizers of science can make it accessible, informative, fun and awe-inspiring all in one breath. Phil pulls it off with ease. Picture a man with the wonder of Carl Sagan crossed with the mischievous curiosity of Adam Savage, multiply their combined enthusiasm by a factor of 10, and you've got yourself a Phil Plait.

The next generation of astronomers will come to the field not via Cosmos, but through Bad Astronomy. The universe may never be the same.

Let's take a tour through some Bad Astronomy. There won't be a quiz at the end, but there'll be one hell of an exciting announcement.

We begin with lift-off. Crank your speakers. Put on your shades. Prepare for escape velocity.

"Space X took the webcam video from their successful launch of the Falcon-1 rocket and set it to music. The result is made of awesome. The editing is a thing of wonder.... And yes, you want the high-def version."

Hell to the yes.

This successful Space X launch means that NASA has some options on the table. With the retirement of the space shuttle, they were looking at having to carve out an exception to the "don't play with those who play with Iran" rule so they could hitch rides on Russian spacecraft. Now, that waiver may no longer be necessary. And we'll have an alternative just in case we manage to piss Russia off enough to get booted off the bus. Hooray for choices!

Speaking of choices, it's going to be hard to choose which observatory to visit when I go back for my super-long trip to Arizona next May. This utterly awesome image was taken at Kitt Peak National Observatory. The work they're doing there is revealing whole new vistas into star formation, as Phil explains:

"So we see galaxy collisions all the time, but sometimes the evidence is weak. NGC 4438 is the galaxy on the left, and it’s all twisty and distorted. M86 is a more normal looking elliptical. But looking at the gas content of M86 has indicated something is going on; it’s heated up pretty well, and distorted. But it wasn’t until now we could see why.

That image above is from a 4 meter telescope in Arizona. It has a camera that allows it to collect a lot of light over a big area of the sky. When a filter was used that isolates warm hydrogen gas, astronomers found these tendrils connecting the two galaxies. Those tentacles are the shrapnel of the impact, streamed out in the aftermath of the collision… and the galaxies are now 400,000 light years apart. That’s four times the size of our Milky Way.

The sciencey part of this is that they looked for new stars being born in those filaments; that’s common after collisions. However, there aren’t any! The collision happened at such high speed that the gas got really hot, and couldn’t condense to form stars. That has implications for the galaxies themselves. It’s been something of a mystery as to why elliptical galaxies stopped forming stars early in their lives. It’s thought the central supermassive black hole in the center of every galaxy plays a part; as the black hole feeds on matter it blows off a huge wind, blowing out the galaxy’s gas and cutting off star formation.

But now we see that collisions may play a role as well, heating up the galaxy’s gas and preventing it from making stars. It’s hard to say how much each process contributes; early in a galaxy’s life it hasn’t had much time to collide with others, so maybe this becomes important later. And spirals have those black holes too, yet stars still form in them. Obviously, there’s a lot of complicated stuff going on."

Do I have to explain the awesome here? I didn't think so.

Speaking of explaining... doesn't it seem sometimes like the Universe is watching your every move? Phil's got an explanation for that:

"This cosmic eye is an illusion. I mean, duh, it’s not an eye. But it’s not even really shaped like one! The shape itself isn’t real. The "pupil" of the eye is actually a galaxy about 2.2 billion light years from Earth. That’s a fair bit! But it happens to sit almost directly between us and a much more more distant galaxy — one that is 11 billion light years away. As the light from the background galaxy passes by the nearer one, the gravity of the nearer one bends the path of that light, twisting it in what’s called a gravitational lens. Arcs are common results of lensing. That’s what you’re seeing here; the distant galaxy image split in two, arcs surrounding the spherical galaxy between them. An eye!"

You can put the paranoia down, now. Pick up some wonder instead. Mercury Messenger is sending us dispatches, and they are astounding. Behold these images:

Phil is, justifiably, beside himself with excitement:

"Holy Haleakala. Look at those rays! They go all the way across the planet!

This is Mercury as seen by MESSENGER, which flew by the planet for a second time yesterday (out of three passes on its way to orbiting the planet in March 2011). This overview was taken when the probe was 27,000 km (17,000 miles) from Mercury, 90 minutes after closest encounter. What you’re seeing here is pretty much the opposite side of the planet as was seen last January at MESSENGER’s first pass, so most of this is territory never seen before in this detail (in this case, at about 5km/pixel).

The bright streaks or stripes are called rays. They’re material ejected from what appears to be a young crater first seen during the initial flyby. When an object impacts the surface of a planet, material can spray out in long rays; check out an image of the full Moon to see similar rays radiating out from the crater Tycho. Amazingly, the rays were known before MESSENGER; radar signals bounced off Mercury from Earth indicated the rays were there. The ray material lying on the surface reflects radar differently than rock, and that was detected even from Earth.

But this is the first time they’ve been seen."

That's one of the things I love the most about science: knowing something's there, and then, when we get a chance to go look, getting to see it for ourselves. There are few things more exciting in life than that anticipation, nothing more thrilling than discovering something new.

I can't wait for the day when we get to see this up close and personal:

"Meet the planet COROT-exo-3b. It orbits a star slightly larger, hotter, and brighter than the Sun. The star is not an unusual one in any way, but the planet is definitely weird: it orbits the star in just over 4 days, which is pretty close in, though not a record breaker in and of itself. What’s bizarre is that it has about the same diameter of Jupiter, but has 21.6 times Jupiter’s mass. That makes it denser than lead.


The mass of this newly discovered planet is pretty freaky. Normally, anything with a mass more than about 15 or so times the mass of Jupiter would be considered a brown dwarf, a "failed star", as some people call them (I don’t). But at the lower end of the brown dwarf mass range, it gets a bit hard to tell the difference between a planet and a BD. Some people say planets and BDs form in different way (planets grow in size from smaller bodies building up over time through collisions, while BDs and stars form from the collapse of material in a nebula); but I don’t like this definition. You could have two objects that look precisely the same, yet one could be a planet and the other a BD, just because they formed in different ways. That strikes me as silly.

Either way, COROT-exo-3b is weird."

The universe is a bizarre place, my child.

Even in our own back yard, we're finding some very odd and spectacular things. Cassini keeps returning outstanding images. And we gets us some raw footage! Astronomy images are usually gussied up for their dates with the public, but this is the real, untouched thing. If this does not jab its finger hard into your sense of wonder trigger and put all its weight into pressing, then you have no sense of wonder:

"Just yesterday, the Cassini spacecraft passed an incredible 25 kilometers (16 miles) off the surface of Saturn’s weird moon Enceladus. This icy ball has plumes of water jetting up from its south pole region, emanating from a series of parallel cracks nicknamed tiger stripes. Cassini flew right through these plumes! The images taken have not been fully processed yet, but the Cassini folks have released a few of the raw images."

"Wow. The surface of Enceladus is entirely covered with ice; see how few craters there are? That means the surface is "new"; if it were older there would be lots more craters. That means the moon is recently (or continuously) resurfaced, which in turn means a dynamic process almost certainly involving water and a liquid interior. The cracks and plates look to be due to ice floes. We see the same sort of thing here on Earth and on Jupiter’s frozen moon Europa."

Fair gives me chills, that does, and it's not even because we're looking at a moon covered in ice.

This is another thing that gives me chills: the idea that we can see another world so clearly from right here on Earth:

"This weird-looking image is the sharpest picture of Jupiter ever taken from the ground. Taken with a device called — are you ready for this? — the Multi-Conjugate Adaptive Optics Demonstrator (or MAD, in an acronymic stretch), it has a resolution better than Hubble’s!

The Earth’s atmosphere roils and waves, distorting ground-based views of the sky. That’s one of the reasons we launch telescopes into space, to get above all that mess. But if you can observe a point-like object such as a star at the same time you observe your target object, it’s possible to compensate for the distortion by taking extremely rapid fire snapshots and measuring the way the star image changes. You then apply a correction to the image, and presto! It’s cleaner.


Moreover, the astronomers making the observation were able to keep it together for two hours, so they made a way cool movie of Jupiter’s rotation.

The image colors are odd because this is an infrared picture. The telescope and detector observed Jupiter at wavelengths of about 2 microns, about three times redder than the human eye can see. At those wavelengths, hydrogen and methane are strong absorbers, meaning they block the light coming from deep down in Jupiter’s atmosphere. What you’re seeing here is light reflecting off of high haze, above the clouds we see in the usual jovian vistas."

This opens new windows into Jupiter's whacky weather, which in turn will lead to new insights into our own. Is that not a delight?

If you've not gone exploring through Phil's blog, I hope this post has convinced you it's high time you started. Then there's one other thing you really must treat yourself to:

"It’s a carton full of my books!


Hot off the press, too. They’ve been shipping to books stores across this great land of ours, just in time for no one to be able to afford them. Oh well, people love to read about imminent destruction during a recession, right?


These ones are going to my contributors (advisors in the book) and family. 10 days to go before they’re available to the public. Better get them now, before they get eaten up.


At last! Death from the Skies! I've been salivating in anticipation since, what, February? Bring on the meteors! Bring on the comets! Bring on the Bad Astronomy!

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