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Posts Tagged ‘astronomy’

The End of Comet ISON

by coldwarrior ( 42 Comments › )
Filed under Academia, Astronomy, Open thread, saturday lecture series, Science at December 7th, 2013 - 8:00 am

Lets put an end to Comet ISON.

 

From our Friends at Spaceweather.com

THE GHOST OF COMET ISON: This morning, Dec. 6th, leading researchers from the Comet ISON Observing Campaign (CIOC) held an informal workshop at the Johns Hopkins Applied Physics Lab. One of the key questions they discussed was, Did Comet ISON survive? It might seem surprising that anyone is still asking. After all, the “comet” that emerged from the sun’s atmosphere on Thanksgiving day appeared to be little more than a disintegrating cloud of dust. This movie from the STEREO-A spacecraft (processed by Alan Watson) shows the V-shaped cloud fading into invisibility on Dec. 1st:

The answer hinges on the contents of that cloud. Is it nothing more than a cloud of dust–or could there be some some fragments of the disintegrated nucleus still intact and potentially active?

A key result announced at the workshop comes from SOHO, the Solar and Heliospheric Observatory. According to the spacecraft’s SWAN instrument, the comet stopped producing so-called Lyman alpha photons soon after its closest approach to the sun. Karl Battams of the CIOC explains what this means: “Without getting technical, Lyman-Alpha is a consequence of sunlight interacting with hydrogen, and if we are not seeing that interaction then it means that the levels of hydrogen (and hence ice) are extremely low. This is indicative of a completely burned out nucleus, or no nucleus at all.”

“The evidence appears strong that at some point approaching perihelion – whether days or hours – Comet ISON likely began to completely fall apart,” he continues. “What remains of ISON now is going to be either just a cloud of dust, or perhaps a few very depleted chunks of nucleus. Either way, it’s not going to flare up at this point and we should assume the comet’s show is over.”

“However, we do need to verify this,” says Battams. “Hopefully the Hubble team can come to the rescue! In mid-December, Hubble will be pointed in the direction of where ISON should be and they’ll try and image something. If no fragments are surviving, or they are tiny, then Hubble will not be able to find anything, but that negative detection will tell us something: namely that ISON is indeed gone for good.”

Stay tuned!

Comet ISON Photo Gallery

Saturday Lecture Series: Astronomical HD

by coldwarrior ( 34 Comments › )
Filed under Academia, Astronomy, Open thread, Science at August 24th, 2013 - 8:00 am

Good morning all! Today’s lecture is on adaptive optics, dry air, and large mirrors. University of Arizona, long time pioneers in astronomical optics, have raised the bar and have made a ground based telescope that has twice the resolution of the venerable Hubble Space Telescope. Our Grad Ass CJ thinks this is just groovy.

 

The below link takes you to an article with plenty of fantastic photos and links so you can learn all about adaptive optics. Have a great Saturday!

Astronomers at the University of Arizona, the Arcetri Observatory near Florence, Italy and the Carnegie Observatory have developed a new type of camera that allows scientists to take sharper images of the night sky than ever before. The team has been developing this technology for more than 20 years at observatories in Arizona, most recently at the Large Binocular Telescope, or LBT, and has now deployed the latest version of these cameras in the high desert of Chile at the Magellan 6.5-meter telescope.

“It was very exciting to see this new camera make the night sky look sharper than has ever before been possible,” said UA astronomy professor Laird Close, the project’s principal scientist. “We can, for the first time, make long-exposure images that resolve objects just 0.02 arcseconds across – the equivalent of a dime viewed from more than a hundred miles away. At that resolution, you could see a baseball diamond on the moon.”

 

Avian Astronomy Basics – Lesson 1

by Bunk Five Hawks X ( 67 Comments › )
Filed under Entertainment, Humor, OOT, Open thread at October 8th, 2012 - 11:00 pm

An intelligent Homerbird describes the daily rotation of the earth in easy to understand terms in front of a skeptical critic; and just like the Homerbird, we’re going to present, in easy to understand terms, the daily edition of
The Overnight Open Thread.

Saturday Lecture Series: A New Theory on Comets

by coldwarrior ( 24 Comments › )
Filed under Academia, Astronomy, Open thread, saturday lecture series, Science at November 27th, 2010 - 8:30 am

Good Saturday everyone! We are going to stay with the astronomy lectures this week.As an update, the SEB on Jupiter that we reviewed last week is continuing to form. Here are some additional images from ALPO-Japan, this group is worth the review.  We will update on this later when the images are more striking.

I ran across the following article last night, it is a new theory on where some of the comets come from.

The Sun Steals Comets from Other Stars:

Nov. 23, 2010: The next time you thrill at the sight of a comet blazing across the night sky, consider this: it’s a stolen pleasure. You’re enjoying the spectacle at the expense of a distant star.

Sophisticated computer simulations run by researchers at the Southwest Research Institute (SWRI) have exposed the crime.

“If the results are right, our Sun snatched comets from neighboring stars’ back yards,” says SWRI scientist Hal Levison. And he believes this kind of thievery accounts for most of the comets in the Oort Cloud at the edge of our solar system.

“We know that stars form in clusters. The Sun was born within a huge community of other stars that formed in the same gas cloud. In that birth cluster, the stars were close enough together to pull comets away from each other via gravity. It’s like neighborhood children playing in each others’ back yards. It’s hard to imagine it not happening.”

According to this “thief” model, comets accompanied the nearest star when the birth cluster blew apart. The Sun made off with quite a treasure – the Oort Cloud, which was swarming with comets from all over the “neighborhood.”

The Oort cloud is an immense cloud of comets orbiting the Sun far beyond Pluto. It is named after mid-20th century Dutch astronomer Jan Oort, who first proposed such a cloud to explain the origin of comets sometimes seen falling into the inner solar system. Although no confirmed direct observations of the Oort cloud have been made, most astronomers believe that it is the source of all long-period and Halley-type comets.

PLEASE READ THE REST HERE

Recently, we had a close flyby of Comet Hartley 2 with some very interesting results:

Comet Snowstorm Engulfs Hartley 2

Nov. 18, 2010: NASA has just issued a travel advisory for spacecraft: Watch out for Comet Hartley 2, it is experiencing a significant winter snowstorm.

Deep Impact photographed the unexpected tempest when it flew past the comet’s nucleus on Nov. 4th at a distance of only 700 km (435 miles). At first, researchers only noticed the comet’s hyperactive jets. The icy nucleus is studded with them, flamboyantly spewing carbon dioxide from dozens of sites. A closer look revealed an even greater marvel, however. The space around the comet’s core is glistening with chunks of ice and snow, some of them possibly as large as a basketball.

For those of you that missed the beautiful flyby pics of Harley 2, here is EPOXIs Home page.