Ring of Fire

Saturn is just past opposition and perfectly placed for viewing in May. It never gets all that high – 45 degrees at transit – but we’ll still get a good look at the ring system, tilted about 13 degrees to us. Don’t forget to watch for storm activity in Saturn’s cloud belts.

Mercury is visible early in the month, but disappears in front of the sun by mid-month.

Venus, too, is visible as May begins, but later disappears in the sun’s glare. But that’s okay – because early next month, on June 5, is the last Venus transit until 2117. Some of you may have seen the last transit, in 2004, though it wasn’t visible from San Jose since it happened in the middle of the night. This year we will get to see the transit – at sunset – so get ready for it!

I’ll have more information about the Venus transit in next month’s column, but for now, be sure you line up a solar filter if you don’t already have one. You don’t need a big telescope – even a 60mm should be plenty to see the transit – and you don’t need a fancy H-alpha filter. Any safe white-light filter will do. But I expect there may be a run on solar filters as we get close to this once (or twice) in a lifetime event, so don’t wait too long!

Mars has shrunk to under 10 arcseconds and zeroth magnitude as it recedes from us. It’ll be tough to see much detail, but I hope you got a chance to look at it when it was closer.

As an example of the sort of detail you can see (at least photographically) in even a distant Mars opposition, consider this news item from last month. An amateur astronomer, Wayne Jaeschke, imaging from Pennsylvania with a 14” SCT, captured what appeared to be clouds on Mars’ limb, towering well up above the terminator. This sort of thing has been seen before on Mars, but usually with much bigger scopes and not so near opposition. There was much speculation on what might cause such a cloud – perhaps a dust storm, or maybe dust kicked up by a meteor impact? Or clouds lit up by a localized aurora?

Professionals jumped in to analyze the formation before it disappeared, and spectroscopy suggested it was probably a water cloud condensing near Mars’ morning terminator. NASA’s Mars Reconnaissance Orbiter showed no unusual dust activity in that region.

So probably just unusual morning clouds – but it’s pretty cool that something like that could be discovered by an amateur.

Jupiter is in conjunction with the sun this month. Uranus, Neptune and Pluto are all morning sky objects this month.

But here’s the big news for the month: On May 20th, we’ll be treated – well, almost – to an annular solar eclipse.

Annular means that the moon is a bit farther away than usual, so it won’t completely cover the sun even if you travel to the eclipse centerline. Since the sun will never be totally covered, make sure you have a safe solar filter for this one – don’t look with your naked eyes! Think of it as a good excuse to try out that new filter you ordered for next month’s Venus transit.

I mentioned that we’ll “almost” see it. Here in San Jose, we’re just a bit south of the southern limit of the annular path, which passes just south of the town of Redway, through Covelo, just south of Willows, then just misses Yuba City and Auburn. If you want to be closer to the centerline, go camping at Lassen National Park or Lake Shasta, or head to Reno or Tahoe.

Here at home, we still get a darn good dinner show. The partial eclipse starts at 5:17 pm PDT, with maximum eclipse at 6:33. It’s 18 degrees above the horizon at that point, and the sun will be 89% eclipsed. Compare that with 97% for a site right on the centerline – remember, since this is an annular eclipse, no place sees 100% coverage. The partial eclipse ends at 7:40 – still well before sunset, which isn’t until 8:11.

It’s been a long time since we had a solar eclipse anywhere near this good visible from home.

Photographers, if you want a shot of an annular eclipse as the sun sets, head east, to Albuquerque, NM or Lubbock, TX. Though it might be tough to balance an exposure that will show the annular ring while still showing the surrounding landscape. The centerline also crosses near a lot of great vacation spots like Bryce, Zion and Canyon de Chelly.

For calculating places and times, NASA has a great interactive page here you can click on a map and get times and coverage for any location: http://eclipse.gsfc.nasa.gov/SEgoogle/SEgoogle2001/SE2012May20Agoogle.html

I just went to put the event on my calendar, and discovered it already had an entry for May 20. It’s the start of Bear Awareness Week.

So if you head up to Lassen or Shasta to watch the eclipse, be sure to be aware of the bears! (Also, maybe I should get a calendar that’s a little more in tune with the sky.)