Category Archives: astronomy

astronomy

Red Moon Coming Your Way

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Moon’s Being Chased by an Earth Shadow

Here’s how the eclipse will play out. Please visit Eclipsewise.com or MrEclipse.com for more details on visibility at your site. Courtesy Fred Espenak.

There’s another lunar eclipse coming up — the second total one this year — and people in most of North and South America, as well as parts of the Pacific, Oceania and Asia will see all or part of it. The sight of a red-colored moon is pretty amazing, and I hope you’ll check it out for yourself.

It begins in the wee hours of October 8th for North and South America and will be an evening sight for everybody else. So yeah, it means you have to get up really early if you live where it occurs after midnight. But, it’s worth it. I stayed up pretty late for the last one, and it really is a spooky, eerie, and ultimately beautiful sight.

The whole eclipse lasts several hours, so it’s not a “quickie” event. If you plan to watch, be sure you’re dressed for the weather. While you’re watching the shadow pageant unfold, use your binoculars or telescope to study the Moon’s surface. It’s a fascinating place to explore.

If you want to know more about eclipses, and this one in particular (and if you aren’t quite sure if you can see it from your location), check out MrEclipse.com, Eclipsewise.com, TimeAndDate.com, Sky&Telescope, and Astronomy magazines online for viewing information.

Viewing chart showing visibility of the October 8, 2014 total lunar eclipse. Courtesy Fred Espenak, Eclipsewise.com

The prospect of a great total lunar eclipse (which occurs at Full Moon) always brings out the loonies. I’ve been reading for months about how these total lunar eclipses are portending ominous things, or “mean” something apocalyptic.

In reality, there’s nothing supernatural about a lunar eclipse. Lunar (and solar) eclipses are predictable, they happen every year (whether partial or total), and they’re part of a regular cycle that occurs as the Moon and Earth move in their orbits. Earth orbits the Sun, the Moon orbits Earth.  And, every once in a while, those motions bring them into alignment with each other (which is itself normal and nothing to be worried about).  When that happens, we can get an eclipse (if all conditions are right.

Fred Espenak (MrEclipse himself) has a lovely discussion of lunar eclipses and how they work, so if you want to dig in a little deeper to understand this completely natural and predictable phenomenon, check it out.  See you next week under the Red Moon!

astronomy

Philae, You are Cleared for Landing on Runway J

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Rosetta Scientists Set a Date for Philae’s Comet Landing

Rosetta's navigation camera (NAVCAM) took this image of Comet 67P/Churyumov-Gerasimenko on 21 September, from a distance of 27.8 km from the comet center. The image covers an area of about 2 x 1.9 km and focuses on the smaller of the two comet lobes. The primary landing site J is 'above' the distinctive depression in this view. ESA/Rosetta/NAVCAM
Rosetta’s navigation camera (NAVCAM) took this image of Comet 67P/Churyumov-Gerasimenko on 21 September, from a distance of 27.8 km from the comet center. The image covers an area of about 2 x 1.9 km and focuses on the smaller of the two comet lobes. The primary landing site J is ‘above’ the distinctive depression in this view. ESA/Rosetta/NAVCAM

On November 12, 2014, the Philae lander will make its way from the Rosetta mother ship to the surface of Comet 67P/Churumov-Gerasimenko and make history at the same time. It will be the first soft landing on a comet, and if all works as planned, Rosetta mission scientists will have a chance to finally sample the surface of one of the solar system’s oldest objects. The area where Philae will land is called “Site J”, and the team is planning on a public contest to help rename the site, which will be announced on October 14th.

So, what is J like?  From the image, it all looks rather dangerous to a spacecraft. When I first looked at this site, I was reminded of the confidence that the Apollo mission planners had for the first human landing on the Moon, only to have that attitude “busted” when astronauts Neil Armstrong and Buzz Aldrin actually GOT to the proposed landing site but had to maneuver a bit to find a REALLY safe place to put down their landing module.

It’s sort of the same situation with Philae. Mission planners didn’t find any broad, flat plain that said, “Here!! Land on ME!!!”  Each region of the comet’s surface has challenges for a spacecraft,  and even settling down on a small boulder could damage the spacecraft. So, they found six possible sites, narrowed it down to two “least of all evils” choices, and then selected the J site as the one with the least problems. The mission planners found it more compelling scientifically and procedurally than any of the other sites.

This image shows the landing site, just above the jagged shadowed area at the center. Most of the surface area within a square kilometer landing target is relatively flat, or has slopes of less than 30 degrees. Also, the area has only a few large boulders, and it receives enough sunlight to recharge Philae regularly. Renewing the lander’s power by sunlight is important — its battery pack has enough juice for about 64 hours before, which will power the lander for the time the scientists and spacecraft are settling in and calibrating and testing the onboard instruments.

This four-image montage shows the spectacular region of activity at the 'neck' of 67P/C-G. This is the product of ices sublimating and gases escaping from inside the comet, carrying streams of dust out into space. ESA/Rosetta/NAVCAM
This four-image montage shows the spectacular region of activity at the ‘neck’ of 67P/C-G. This is the product of ices sublimating and gases escaping from inside the comet, carrying streams of dust out into space. ESA/Rosetta/NAVCAM

Of course, there’s some chance that Site J will turn out to be unworkable. In that case, the Rosetta mission planners have a backup site, called “C”.  It also promises good science and relatively good solar illumination for the spacecraft’s power system.

By the way, just to give you an idea of what the scientists are facing in searching out a landing site:  this comet is an active one!  It’s tumbling as it moves through space AND there are jets shooting out from beneath its surface.

The final decision about the site and landing will be made on October 14th, based on the latest available data and images taken by Rosetta’s cameras. I can’t wait to see where they finally end up landing, and, of course, the cool pictures! We know there ARE many cool images already taken, but they haven’t yet been released to the public.  Yet. Not sure when they will be. But, in any case, stay tuned! A spacecraft landing on a comet is NOT something you don’t see every day!