Starship Asterisk*

• Jupiter's Impact: Gone in 30 Days
  Sky & Telescope - 2009 August 21
  
  
  
  The impact scar on Jupiter has spread sideways and broken up
  into faded, feathery bits. Yellow ticks mark its approximate ends
  in images taken 75 minutes apart on August 17, 2009, when the
  System II central-meridian longitude was 182° (top) and 227°.
  
  Christopher Go

bystander wrote:

apodman wrote:That's a good question. If the km and miles are right, the arcseconds are wrong. If the arcseconds are right, the km and miles are wrong. Or they could both be wrong.

If your math is right, the arcseconds are wrong. In Fast Facts it gives the distance to Jupiter as 386 million miles.

The semi-major axis of Jupiter's orbit about the sun is 5.2 astronomical units (483 million miles or 778 million km). On July 23, 2009 Jupiter was 368 million miles from Earth.

apodman wrote:Unfortunately, the limb of Jupiter is too fuzzy in the picture for me to measure A and B with much confidence. Perhaps someone else would like to try.

apodman wrote:

geckzilla wrote:Ooooh, ok. So is the line itself to scale then? It must be just the arcseconds which are wrong.

That's a good question. If the km and miles are right, the arcseconds are wrong. If the arcseconds are right, the km and miles are wrong. Or they could both be wrong.

apodman wrote:That's a good question. If the km and miles are right, the arcseconds are wrong. If the arcseconds are right, the km and miles are wrong. Or they could both be wrong.

The semi-major axis of Jupiter's orbit about the sun is 5.2 astronomical units (483 million miles or 778 million km). On July 23, 2009 Jupiter was 368 million miles from Earth.

geckzilla wrote:Ooooh, ok. So is the line itself to scale then? It must be just the arcseconds which are wrong.

Joe Stieber wrote:at Jupiter's distance of 4.10 AU on the day it was taken (July 23, 2009), it should be:

10,000 mi = 16,100 km = 5.4"
or
10,000 km = 6,200 mi = 3.4"

Looks like another metric mix-up. I tried contacting folks at the Hubble Site (home of the original press release for this picture) and the STScI, but I might as well have tried to contact a brick wall. As of today, the image with the erroneous scale is still up at the Hubble Site:

http://hubblesite.org/newscenter/archiv ... web_print/

mark swain wrote:Are there any angles, that we see our solar system is at,,, in our galaxy? Criptic.. Is our sun, and the planets on a flat plain to the center of the milky way? North/East/South/West ?

http://www.internationalastrologers.com/galactic_equator.htm wrote:

http://seds.org/~spider/spider/ScholarX/coords.html wrote:The galactic north pole is at RA = 12:51.4, Dec = +27:07 (2000.0), the galactic center at RA = 17:45.6, Dec = -28:56 (2000.0). The inclination of the galactic equator to Earth's equator is thus 62.9 deg. The intersection, or node line of the two equators is at RA = 18:51.4, Dec = 0:00 (2000.0), and at l = 33 deg, b=0.

http://en.wikipedia.org/wiki/2009_Jupiter_impact_event wrote:
<<The 2009 Jupiter impact event, occasionally referred to as the Wesley impact, was a July 2009 impact on Jupiter that caused a black spot in the planet's atmosphere. The spot was similar in size to the planet's Little Red Spot and about the size of the Pacific Ocean. The impact scar is expected to last only a week or two as it becomes diluted by Jupiter's atmosphere.

Amateur astronomer Anthony Wesley discovered the impact at approximately 13:30 UTC on 19 July 2009 (almost exactly 15 years after the Jupiter impact of comet Shoemaker-Levy 9, or SL9). He was at his home observatory just outside Murrumbateman, New South Wales, Australia, using stacked images on a 14.5-inch diameter reflecting telescope equipped with a low light machine vision video camera attached to the telescope.

Wesley stated that: "When first seen close to the limb (and in poor conditions) it was only a vaguely dark spot, I [thought] likely to be just a normal dark polar storm. However as it rotated further into view, and the conditions improved I suddenly realised that it wasn't just dark, it was black in all channels, meaning it was truly a black spot."

Wesley sent an e-mail to others including the NASA Jet Propulsion Laboratory in Pasadena, California reporting his observations.

Paul Kalas and collaborators confirmed the sighting. They had time on the Keck II telescope in Hawaii, and had been planning to observe Fomalhaut b, but they spent some of their time looking at the Jupiter impact. Infrared observation by Keck and the NASA Infrared Telescope Facility (IRTF) at Mauna Kea showed a bright spot where the impact took place, indicating the impact warmed a 190 million square km area of the lower atmosphere at 305 W, 57 S near Jupiter's south pole.


Large impact observed with Keck II telescope and its near-infrared camera at Mauna Kea on July 20 11:20 UT

The spot's prominence indicates that it is composed of high-altitude aerosols similar to those seen during the SL9 impact. Using near-infrared wavelengths and the IRTF, Glenn Orton and his team detected bright upwelling particles in the planet's upper atmosphere and using mid-infrared wavelengths, found possible extra emission of ammonia gas.

The force of the explosion on Jupiter was thousands of times more powerful than the suspected comet or asteroid that exploded over the Tunguska River Valley in Siberia in June 1908. (This would be over a million times more powerful than the bomb dropped on Hiroshima.)

The object that hit Jupiter was not identified before Wesley discovered the impact. A 2003 paper estimated comets with a diameter larger than 1.5 kilometers impact Jupiter about every 90 to 500 years, while a 1997 survey suggested that the astronomer Cassini may have recorded an impact in 1690.

Given the size of the SL9 impacters, it is likely that this object was less than one kilometer in diameter. Finding water at the site would indicate that the impacter was a comet, as opposed to an asteroid or a very small, icy moon. It is more likely that the object was a comet since comets generally have an unstable orbit. At the distance of Jupiter (5.2 AU) most small comets are not close enough to the Sun to be very active.

Assuming it was an inactive comet (or asteroid) about 1 km in diameter, this object would have been no brighter than about apparent magnitude 25. (Jupiter shines about 130 billion times brighter than a 25th magnitude object.) Most asteroid surveys which use a wide field of view do not see fainter than about magnitude 22 (which is 16x brighter than magnitude 25). Even detecting satellites less than 10 km in diameter orbiting Jupiter is difficult and requires some of the best telescopes in the world; it is only since 1999 with the discovery of Callirrhoe that astronomers have been able to discover many of Jupiter's smallest moons.>>

billMe wrote:Oh, it's based on our perspective. Thanks!

billMe wrote:this is incredibly simple compared to previous posts but what do the arrows on the image mean?

N is up and E is to the left?