Starship Asterisk*

by **bystander** » Fri Mar 25, 2016 4:25 pm

Dark Object Investigated While Making One of the Closest Ever Comet Flybys of Earth
Planetary Science Institute | 2016 Mar 24

Astronomers at the Planetary Science Institute made observations of Comet Pan-STARRS (P/2016 BA14) using the NASA Infrared Telescope Facility (IRTF) on Mauna Kea, Hawai’i that show that it reflects less than 3 percent of the sunlight that falls on its surface. For comparison, fresh asphalt reflects about 4 percent of the light that falls on it.

Comet Pan-STARRS made a close flyby of the Earth at a distance of 3.6 million kilometers (2.2 million miles) on March 22. This is one of the closest flybys of a comet in recorded history and the last one to come closer was Lexell’s comet that flew by the Earth at a distance of 2.2 million kilometers (1.4 million miles) on July 1, 1770. ...

by **bystander** » Fri Mar 18, 2016 10:18 pm

A 'Tail' of Two Comets
NASA | JPL-Caltech | 2016 Mar 18

by **starsurfer** » Fri Mar 18, 2016 6:04 pm

Ann wrote:The comet and the galaxy make for a particularly lovely pair.

The colors are great. The green color of the comet is striking. Note that the great star clusters and OB associations of the Large Magellanic cloud are noticeably bluer in color than the comet, but the bright Tarantula Nebula at upper left of center is aqua-colored. I have to wonder if we are seeing the OIII emission of this great nebula. The bar of the LMC, made up of older stars, is rather reddish.

Note that the second largest cluster complex of the Large Magellanic Cloud is visible at bottom right.

Ann

The nebulae in the LMC do have a lot of OIII but some amateur astrophotographers suppress it in favour of the red Ha emission.

by **Ann** » Fri Mar 18, 2016 10:53 am

heehaw wrote:Hey, what happened to Cassiopeia ? It's 5:24 Eastern!

You can find the Cassiopeia discussion page here.

But I agree, it should have been fixed by now. I guess no one has informed whoever should have corrected it.

Ann

by **heehaw** » Fri Mar 18, 2016 9:25 am

Hey, what happened to Cassiopeia ? It's 5:24 Eastern!

by **Jim Leff** » Thu Mar 17, 2016 8:55 pm

Rob -

OMG! Runner-Up: Celestron Cometron 7x50 (Cost: $30)

That's just crazy! I'll order NOW!

4.5 stars on Amazon, too....

by **Fred the Cat** » Thu Mar 17, 2016 7:30 pm

rstevenson wrote:
Jim Leff wrote:...I should pick up a cheap pair of binoculars for marginal situations like this. Can anyone recommend an unserious, inexpensive pair for informal viewing? Preferably one that minimizes hand-shake (I'm not gonna use a tripod)?
I've used a Nikon Action 8x40 for the last 7 years. There are certainly better binoculars for astronomical viewing, but these are handy and inexpensive.

But have a look at this Space.com article, and check out the price of the runner-up for best small binocular!

Rob

These are great with these. A little higher end but $500 and you are good to go. They do work better under dark skies but the Pleiades fill up your viewing field.

by **rstevenson** » Thu Mar 17, 2016 7:02 pm

Jim Leff wrote:...I should pick up a cheap pair of binoculars for marginal situations like this. Can anyone recommend an unserious, inexpensive pair for informal viewing? Preferably one that minimizes hand-shake (I'm not gonna use a tripod)?

I've used a Nikon Action 8x40 for the last 7 years. There are certainly better binoculars for astronomical viewing, but these are handy and inexpensive.

But have a look at this Space.com article, and check out the price of the runner-up for best small binocular!

Rob

by **Jim Leff** » Thu Mar 17, 2016 6:04 pm

Thanks. Wow, that's exciting.

I'm close enough to NYC that the seeing is lousy. But I should pick up a cheap pair of binoculars for marginal situations like this. Can anyone recommend an unserious, inexpensive pair for informal viewing? Preferably one that minimizes hand-shake (I'm not gonna use a tripod)?

by **Chris Peterson** » Thu Mar 17, 2016 3:29 pm

Jim Leff wrote:We can assume neither's expected to be naked-eye visible, or the explanation would have said so, right?

I would not assume that. A few nights ago Australian observers were reporting m=5.8 for 252P, which is already borderline naked-eye, and it's still brightening. So I'd expect that, at least, for good observers under dark skies this will be naked-eye. And an easy binocular comet for many more. Of course, it's hard to know just what an oddball comet like this will do (it was originally predicted to reach a maximum brightness of only +13!)

by **Jim Leff** » Thu Mar 17, 2016 3:20 pm

We can assume neither's expected to be naked-eye visible, or the explanation would have said so, right?

by **Chris Peterson** » Thu Mar 17, 2016 1:50 pm

There's a lot going on with these comets. 252P is MUCH brighter than expected, its rapid brightening consistent with current or very recent fragmentation, which may explain BA14. More fragmentation is possible. This is reminiscent of Comet Biela, which fragmented (and was apparently destroyed) in the mid nineteenth century, but the debris of which remains as the Andromedid meteor shower. This pair of comets passes near enough the Earth that they may also create minor meteor showers (both southern, with radiant declinations of -16° and -39°).

252P will be back around in five years. BA14, maybe not, as it's only around 100 meters in diameter, meaning there may not be much left after this perihelion.

by **Ann** » Thu Mar 17, 2016 5:48 am

The comet and the galaxy make for a particularly lovely pair.

The colors are great. The green color of the comet is striking. Note that the great star clusters and OB associations of the Large Magellanic cloud are noticeably bluer in color than the comet, but the bright Tarantula Nebula at upper left of center is aqua-colored. I have to wonder if we are seeing the OIII emission of this great nebula. The bar of the LMC, made up of older stars, is rather reddish.

Note that the second largest cluster complex of the Large Magellanic Cloud is visible at bottom right.

Ann

by **APOD Robot** » Thu Mar 17, 2016 4:08 am

Close Comet and Large Magellanic Cloud

Explanation: Sporting a surprisingly bright, lovely green coma Comet 252P/Linear poses next to the Large Magellanic Cloud in this southern skyscape. The stack of telephoto exposures was captured on March 16 from Penwortham, South Australia. Recognized as a Jupiter family periodic comet, 252P/Linear will come close to our fair planet on March 21, passing a mere 5.3 million kilometers away. That's about 14 times the Earth-Moon distance. In fact, it is one of two comets that will make remarkably close approaches in the next few days as a much fainter Comet Pan-STARRS (P/2016 BA14) comes within 3.5 million kilometers (9 times the Earth-Moon distance) on March 22. The two have extremely similar orbits, suggesting they may have originally been part of the same comet. Sweeping quickly across the sky because of their proximity to Earth, both comets will soon move into northern skies.

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