Venus cleared the trees in a dark sky this morning just before the start of morning twilight. To the right of the planet is the star Spica. Up top is Saturn. Details: 35mm lens at f/2.8, ISO 800 and 30-second exposure. Photo: Bob King
Things don’t always work out as you anticipate. Last night, I’d hoped to see the dark clouds of the SEB revival that announce the return of Jupiter’s equatorial stripe, but even in a 10-inch telescope, I couldn’t make them out. Ditto for the northern lights. Despite a cheery forecast earlier in the day, the northern sky was dead. No lights. Clouds early in the evening prevented viewing a newly discovered asteroid that passed only 20,000 miles over my house. By the time the sky cleared, it had already moved on, become too faint to spot in a scope. Then this morning, I dutifully stood out in the 22-degree chill hoping to see a few Leonid meteor flashes, but the miserly lion wouldn’t part with a single one. When your hopes aren’t met, it’s wise to have a backup plan. Mine was seeing the planet Saturn through the telescope and Venus ablaze below it. As Woody Allen once said: “80% of life is just showing up.” By the way, don’t let my experience with the meteor shower dissuade you from getting up for a look tomorrow morning. You might just hit it right.
A beautiful shot of Comet Ikeya-Murakami taken on the morning of November 14. A suitable instrument and time exposure photography reveal a much more striking comet than can currently be seen in amateur telescopes. Credit: Michael Jaeger
I also checked up on the Japanese comet Ikeya-Murakami, still in the constellation Virgo about five degrees below Saturn. To my surprise, it has nearly faded away! In a 15-inch telescope at the very start of morning twilight, the comet took a lot of concentration and coaxing to distinguish from the sky background. On the other hand, our old friend Comet Hartley 2, now in the constellation of the Unicorn (Monoceros), is still faintly visible in ordinary binoculars.
A computer simulation of Earth's dust tail/ring seen from a vantage point outside our solar system. Colors indicate density; purple is lowest, red is highest. Credit: Christopher Stark, GSFC
While we’re on the topic of comets, it looks like our very own Earth has a tail, too. NASA’s Spitzer Space Telescope, which can detect the faint glow given off by sun-warmed dust motes, passed through it a few months ago.
“As Earth orbits the sun, it creates a sort of shell or depression that dust particles fall into, creating a thickening of dust â€“ the tail â€“ that Earth pulls along via gravity,” explained Spitzer Project scientist Mike Werner. “In fact, the tail trails our planet all the way around the sun, forming a large dusty ring.” The dust doesn’t originate from the Earth or those shelves you haven’t touched in a month, but rather from the breakup of asteroids and material strewn by comets along their orbital paths. Astronomers have found dust disks around 20 stars to date. Bumps, tails and warps in those disks have led to the discovery of a number of planets. The planets themselves might be too tiny to be obvious or lost in the glare of their host stars, but the warps are much larger and easier to image.
This diagram shows Fomalhaut, its planet Fomalhaut b and the dust disk. Credit: NASA/ESA/A. Feild
“In some stars’ dust disks, there are bumps, warps, rings, and offsets telling us that planets are interacting with the dust,” explains Mark Clampin of NASA’s Goddard Space Flight Center. “So we can ‘follow the dust’ to the planets.Â That’s exactly what happened in 2005, when astronomers inferred the existence of a planet around the bright star Fomalhaut (FOE-ma-low) in Pisces Austrinus by the sharp inner edge of the star’s dust disk. They had a hunch that a hidden planet was herding material. Three years later, the Hubble Space Telescope nabbed Jupiter-sized Fomalhaut b, the star’s planetary companion.
I’m thrilled Earth has a tail. Perhaps alien astronomers will one day find us because we’re so good at making waves. For more on the topic, check out this NASA release.
Do you dig the planet Jupiter? Do you have a telescope, even a small one? Then tonight you’ll have reason to stay glued to the eyepiece for a six-part ‘performance extraordinaire’ of the planet’s moons. Here’s the schedule – all times are Central Standard. If you’re on the East Coast add an hour, mountain states subtract an hour and along the West Coast, subtract two hours.
5:46 p.m. The shadow of the moon Europa appears over Jupiter’s cloudtops along the planet’s eastern edge. It will take about 2 1/2 hours to move to the western edge.
6:08 p.m. Europa itself departs Jupiter’s disk and appears like an earring pinned to its western edge.
6:34 p.m. Io reappears from being eclipsed by Jupiter’s shadow 1/2 of a Jupiter diameter to the planet’s east. Watch it materialize from the darkness.
7:15 p.m. Ganymede gets occulted or covered up by Jupiter at the planet’s east edge.
8:29 p.m. Europa’s shadow exits Jupiter’s disk.
9:06 p.m. Ganymede – nearby east of the planet – slowly disappears into Jupiter’s shadow during eclipse. To catch it fading, be watching a little beforehand.