Hubble View: Jupiter Impact (2009 July 31)

[billMe]

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?

http://apod.nasa.gov/apod/ap090731.html

[neufer]

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?

[billMe]

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

[Chris Peterson]

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

Sort of, but the legend is definitely confusing. It is showing how the image matches the sky: "north" means the direction that declination is increasing, and "east" means the direction that right ascension is increasing. But in this closeup image of Jupiter, the legend might be interpreted as referring to the planet's coordinate system, and that would be incorrect. As we see Jupiter in the image, north is up but west is to the left. That is, in this image, longitude is increasing to the left.

[neufer]

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<<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.>>

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http://antwrp.gsfc.nasa.gov/apod/ap031003.html

[The Code]

Imput...

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 ?

Mark

[apodman]

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 ?

The plane of our solar system is the ecliptic. The plane of the milky way is the galactic equator. The two planes are inclined to each other.

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/Galactic_coordinate_system

[The Code]

Thx Apodman

Always good to get a perspective.. nice one..

mark

[Joe Stieber]

I know this is sort of late (I just finally joined this discussion board), but the real problem with this picture is the scale bar. It's labeled:

10,000 mi = 16,100 km = 3.4"

However, 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/

[geckzilla]

I'm confused about how you figure that. You seem to be basing your calculation on the distance of Jupiter from Earth?

[apodman]

Using rough conversion factors for miles/AU and km/AU:

---

4.1 AU x 93,000,000 miles/AU = 381,300,000 miles

10,000 miles / 381,000,000 miles = 1/38,130

arctan (1/38,130) = .0015 degrees
or
arcsin (1/38,130) = .0015 degrees

.0015 degrees x 3600 arcseconds/degree = 5.4 arcseconds

---

4.1 AU x 149,600,000 km/AU = 613,360,000 km

16,100 km / 613,360,000 km = 1/38,097

arctan (1/38,097) = .0015 degrees
or
arcsin (1/38,097) = .0015 degrees

.0015 degrees x 3600 arcseconds/degree = 5.4 arcseconds

---

4.1 AU x 93,000,000 miles/AU = 381,300,000 miles

6,200 miles / 381,000,000 miles = 1/61,452

arctan (1/61,452) = .00093 degrees
or
arcsin (1/61,452) = .00093 degrees

.00093 degrees x 3600 arcseconds/degree = 3.35 arcseconds

---

4.1 AU x 149,600,000 km/AU = 613,360,000 km

10,000 km / 613,360,000 km = 1/61,336

arctan (1/61,336) = .00093 degrees
or
arcsin (1/61,336) = .00093 degrees

.00093 degrees x 3600 arcseconds/degree = 3.35 arcseconds

[neufer]

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/

Does this mean that Hubble will end up crashing into Jupiter

[geckzilla]

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

[apodman]

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.

[bystander]

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.

[neufer]

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.

The Hubble crew would certainly know what the arc seconds were.
The yardstick was clearly originally set up to be 10,000 km.

However, when the press requested English measurements the NASA press release staff screwed it all up.

(Speaking as one who often had to have things filtered thru the NOAA press release staff.)

[apodman]

The math works both for 3.4" = 10,000 km and for 5.4" = 10,000 miles.

The question is what scale matches the actual size of the features on the planet. If we could see more of the planet, we could compare its size to the scale to see for sure which is correct. The equatorial diameter of Jupiter at a distance of 4.1 AU is about 48 arcseconds.

arctan (143,000 km / 613,360,000 km) = .01336 degrees = 48 arcseconds

I tend to think neufer is correct that the Hubble crew knew the arcsecond measurement and converted wrong.

---



Recall from high school geometry class that, if the line segment (diameter) of length C+B passes through the center of the circle and the line segment (chord) of length A+A is perpendicular to it, then A²=C*B. With a little rearrangement of terms, we find that the diameter D of the circle is D=(A²+B²)/B. So all I need to do is measure A and B with the scale on the picture, calculate D, and compare D with the actual diameter of Jupiter. The equatorial diameter of Jupiter is about 143,000 km and the its polar diameter is about 133,700 km, so we're looking for something in between. 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.

[neufer]

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.

I came to the same fuzzy conclusion and punted.

Perhaps someone knows how big the white ovals are.

[Joe Stieber]

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.

Actually, the "Fast Facts" value of 368 (not 386) million miles is wrong too. It works out to about 3.96 AU. At the time the picture was taken (23-July-2009 at 19:00 UT per Fast Facts), a couple of planetarium programs (Stellarium and SkyTools 3) as well as Sky & Telescope's online Jovian moon calculator, put the distance at 4.1 AU. More importantly, the U.S. Naval Observatory's MICA 2.1 software has the distance to Jupiter as 4.101 AU for the designated time. That's about 381,212,000 miles. However, this relatively small error would not account for the larger inconsistencies with the scale bar.

I checked my notes and I had done some measuring of features in the various pictures at the Hubble Site press release (i.e., I measured the scale bar and a feature on the image with the scale bar, then measured the same feature on one of the wider-field images where I could estimate the diameter of Jupiter as a reference). I came up with a value of 11,000 km for the scale bar -- which is surprisingly close to 10,000 km considering my crude measurements -- and therefore, 3.4" would be correct for the bar itself (but the stated miles and kilometers are wrong). Perhaps they intended to present it as a 10,000 mile scale bar, but got a bit mixed up.

[bystander]

• 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

[neufer]

http://www.youtube.com/watch?v=Ie_eiv4zzxk

[geckzilla]

Was there some other impact on any planet within the last five years? I'm having a really confused moment because I thought Shoemaker-Levy 9 impacted more recently. I thought I read some articles very soon after it happened and saw some photos. Now I can't figure out if I did read about it and I was really just 10 years old when it happened or if I am thinking of something else or maybe I first read about it a few years ago and somehow assumed it had just happened. Talk about a time warp...