Blogs / Bad Astronomy

Last week, the NASA spacecraft Cassini dove through the water and dust plumes erupting from Saturn’s moon Enceladus. It was a success! As Carolyn Porco said,

Yesterday’s grazing flyby over the equatorial regions of Enceladus and through its south polar plume went spectacularly well. Several of the Cassini instruments successfully collected valuable information about the south polar surface and the gaseous/particulate environment above it, and we imaging scientists didn’t do too badly ourselves.

She’s not kidding; the images are incredible. Emily, of course, has already been posting about them; see here and here. My favorite so far is this one:

It shows the north pole of Enceladus, which is heavily cratered. Like Jupiter’s moon Europa, Enceladus is encrusted in water ice, which is why it is so white and why there are large smooth regions; cracks in the surface can let water pour through and refreeze. It’s thought the moon may have an undersurface ocean like Europa does as well.

You can read more about the Cassini dive in their press release.

My friend Jim Oberg wrote a very cool article about a very cool event: Vanguard 1, the oldest surviving satellite still in orbit, turned 50 a few days ago. It’s actually outlived most of the people who put it in orbit.

Imagine! 50 years in space. 197,000 orbits. I would love to have this satellite brought back some day; studying just the impacts it’s survived would probably be very helpful in designing future spacecraft. But then, maybe we should leave it in place. 50 years is a long time, and maybe keeping it there will serve as a reminder of how far we’ve come, and how far we have yet to go.

I was recently interviewed by Dale Basler and Brian Bartel from Lab Out Loud, a podcast for the National Science Teachers Association, and it’s now online. I was a member of NSTA for several years back when I was doing education workshops at Sonoma State University. They do great work for teachers across the country, equipping them with the science they need to educate students, so I was really happy to do the interview.

We talked about eggs and the equinox, my first and second books, and spent most of our time talking about the need for skepticism, especially in the classroom. I suggest going to their site and taking a look around, or you can download the interview MP3 directly.

Turns out they had a warmup interview with someone else as a prelude, an apertif if you will, for mine, too. Think of it as a calamari appetizer.

BABloggee and webmaster of the fantastic What’s The Harm? website Tim Farley pointed out to me that NASA has released an incredible picture of the Space Shuttle Endeavour:

The picture was taken from the space station using a telephoto, and the linked page goes to a huge 1.6 Mb picture that’s 1200×800 3000×2000 pixels. It’s really quite stunning!

… but Tim also pointed out to me that you can see something sitting on the window console:

I wonder if they have one of those little FM transmitters so it’s hooked up to the dashboard radio.

I guess having an iPod inside the Shuttle is as useful as an OMS pod outside!

Jupiter’s magnetic field is enormous, which is fitting for the King of the Planets. It is far stronger and larger than Earth’s, and, not surprisingly, far more complex. Still, some parts of it are just like home: Jupiter has aurorae.

This has been known for years; the interaction of Jupiter’s magnetic field with its atmosphere creates the northern and southern lights in much the same way that it happens on Earth. But Jupiter has something we don’t: a volcanically active moon.

Io spews sulfur from a series of volcanoes on its surface. The sulfur atoms go up into space, get ionized, and interact with Jupiter’s magnetic field as well. Waves of electromagnetic energy are created, and these travel along the magnetic field lines, slamming into Jupiter’s atmosphere. Io is, in a way, connected to Jupiter, and you can see this connection, literally, as a bright spot of ultraviolet light on Jupiter.

Like on Earth, this happens in both of Jupiter’s hemispheres, producing a Jovian equivalent of northern and southern lights. As Jupiter rotates, the connection spot leaves a glowing trail that fades with time, so it looks like a spiral-shaped comet on the top of Jupiter’s atmosphere. By studying that spot and trail, scientists can learn about the planet, the moon, the magnetic field, and their interaction… and get a surprise or two in the process, too. A new paper just released shows that something unexpected has turned up in Hubble images of Io’s UV footprint: a leading spot, ahead of the main bright spot.

That’s weird! The bright spot is the place where Io is connected magnetically to Jupiter, so you simply don’t expect to see a spot ahead of that one. Yet there it is. The scientists noticed something else, too: when there is a leading spot in Io’s footprint in one hemisphere of Jupiter, there are multiple spots in the other hemisphere. This led to think that there is more going on here than previously thought. Evidently, there is some sort of magnetic connection between the north and south pole of Jupiter, directly from Io’s northern footprint to its southern one. Something like what happens in a CRT, beams of electrons are being guided from one pole of Jupiter to the other. Compared to the main connection to Io, the connecting beam is weak, so the leading spot is dim, but it’s there.

Here’s what they think is happening: Io blasts sulfur into space. This forms a torus, a doughnut-shaped region of plasma surrounding Jupiter (yellow-green in the illustration above). The magnetic field of the giant planet ionizes the sulfur. As Jupiter’s magnetic field whips past Io, it connects with the moon, and waves of energy flow from Io to Jupiter, creating the bright footprint spot and trail (not shown, but the stream is in blue). The spot is connected to its opposite-hemisphere counterpart by the electron beam (shown in red), and that’s what creates the leading, fainter spot.

This is all very complicated, of course. Jupiter makes a fiercely complex system, and studying it can be very difficult. Observations like this can really mix things up, but the good news is that new data always point us in the right direction, toward truth. And the better news is that in September astronauts will attempt to fix Hubble’s premier ultraviolet camera, called STIS (it’s the camera I worked on in Days Gone By). When it’s fixed, we’ll be able to get higher-resolution images that can see fainter spots, so the picture of Jupiter’s connection with Io will literally become clearer.

Don’t be dissing my posse at Mythbusters, or Zombie Feynman and I will have to kick your butt and eat your brains.