Discovery of 7 new satellites of Jupiter

Great information larry. I live on the Big Island, and I can see the observatories on Mauna Kea from my second story lanai (porch to mainlanders).

It would behard to describe how incredibly beautiful the night sky is on a clear night - The stars look so close you feel like you could reach out and touch them. I'm at 4,400 feet and the observatories are around 14,000 feet. And it's a fun drive up Saddle Road on the way there. It's a moonscape.

Thanks again, good posting.

seaglass

Thanks seaglass - is the general public ever allowed to look through the telescopes? Growing up in the Washington, D.C. area, I never realized how much more you can see in a more remote area until I lived in the Colorado Rockies for a winter. Stunning! Wish I'd had a telescope when I lived there.

Wow, 47 satellites! Do I hear 50? I remember when we only knew of I think 12.

Absolutely fabulous...incredible actually....
and yes,
I second Jes with..gosh I remember learning about the planets when all we knew was that there were like 13

Did you all check out that graphic? All the satellites' orbits.... That's amazingly busy space around Jupiter!

You are lucky for that sight, Seaglass.

Light pollution screws things up for us where I live.

The universe is an interesting place -- that's for sure.

In September, Jupiter will lose a satellite, one sent from earth, at least - the Galileo-Millenium Mission will end when the spacecraft is intentionally crashed into Jupiter. A little bit about it:

http://galileo.jpl.nasa.gov
http://www.jpl.nasa.gov/galileo

Galileo was launched in October 1989 from space shuttle Atlantis with the mission of studying Jupiter and its moons in more detail than ever before.

This Year on Galileo
November 5, 2002 - September 20, 2003

The Story So Far...

As usual for the combination of an aging spacecraft and an intensely
energetic environment, Jupiter dealt Galileo a temporarily crippling blow
during our flyby of Amalthea on Tuesday, November 5, 2002. Approximately 17 minutes after zipping by the tiny satellite at over 18 kilometers per second (41,000 miles per hour), as the spacecraft neared its closest approach to the giant planet, the intensity of the radiation caused a failure in computer circuitry that handles timing of the events on the spacecraft. This caused the computer to switch to a set of backup circuitry, which is a serious enough change to warrant the computer to declare an emergency, shut down operations, and phone home for help. Even in this relatively quiet state for the spacecraft, the radiation environment was still raging, and several additional faults triggered repeated software requests to place (or in this case, keep) the spacecraft computers in safe mode. . .

Since very few communications passes are scheduled with the giant antennas of NASA's Deep Space Network between now and September, on January 15, the spacecraft was instructed not to worry if it doesn't hear from ground controllers.

The Story Yet To Come...

Playback of the recorded Amalthea and Jupiter radiation environment data continued until Friday, February 28. At that time, the playback process was stopped, and the tape recorder, that workhorse of data collection and return for Galileo over the past seven years, wass consigned to a well-deserved retirement . . .

At this time, the high level of spacecraft monitoring via the Deep Space Network antennas that has characterized the past thirteen years drops to one contact per week, just enough to verify the health and status of the craft, and to verify that it is still on the correct trajectory. With the exception of a few flight controllers, the flight team, which once numbered in the hundreds, has moved on to other projects, other jobs, other lives.

The distant orbital loop takes the spacecraft farther from Jupiter than it has been since before entering orbit in December 1995. On April 14, Galileo reaches 370 Jupiter radii (26.4 million kilometers or 16.4 million miles) from the planet. This is about 1/6 the distance from Earth to the Sun, and light takes nearly a minute and a half to travel from Jupiter to the spacecraft!

During the summer months, as the Earth proceeds in its own orbit about the Sun, Jupiter, with Galileo in tow, appears to pass behind the Sun, an event known as Solar Conjunction. This limits our ability to hear from the spacecraft, due to interference from the Sun's turbulent atmosphere. Between Monday, July 28 and Monday, September 15, the radio signal from Galileo changes to put more power into the carrier signal, giving the ground antennas a better chance to receive the signal.

Between Tuesday, August 11, and Monday, September 1, the spacecraft is within 7 degrees of the Sun as seen from Earth, and communications of any sort are not expected. The spacecraft appears to be closest to the Sun on Friday, August 22, when the separation between the two is only 0.83 degrees.

On Thursday, September 18, Galileo is again streaking in towards Jupiter, and reaches 50 Jupiter radii (3.6 million kilometers or 2.2 million miles from the planet. Finally on Saturday, September 20, just before 6 p.m. Pacific Daylight Time, Galileo is just over 18 Jupiter radii out, and a scant 19 hours before impact with the clouds.

For the conclusion of Galileo's trek through the solar system, tune in
again in early September!

For more information on the Galileo spacecraft and its mission to Jupiter,
please visit the Galileo home page at one of the following URL's:

http://galileo.jpl.nasa.gov
http://www.jpl.nasa.gov/galileo

Interesting stuff Larry. Thanks :-)

Kind of sad they are going to kill that spacecraft by crashing it into the planet, but I guess they may learn a lot from doing it.

The Great Dark Spot

The Great Dark Spot
NASA Science News
March 12, 2003

The Cassini spacecraft has photographed an extraordinary dark cloud on Jupiter twice as big as Earth itself.

For more than a century astronomers thought that the Great Red Spot was the biggest thing on Jupiter. Not anymore. Images from NASA's Cassini spacecraft have revealed something at least as large.

The Great Dark Spot.

"I was totally blown away when I saw it--a dark cloud twice as big as Earth swirling around Jupiter's north pole," says Bob West, a planetary scientist at the Jet Propulsion Laboratory.

West has been chasing this cloud for some time. He first saw it--"just a glimpse," says West--in an ultraviolet (UV) picture of Jupiter taken by the Hubble Space Telescope in 1997. But it only appeared in one image out of many spanning a period of years. "I didn't know what to make of it," he recalls.

Now he knows. "The Cassini spacecraft was en route to Saturn in 2000 when it passed by Jupiter and had a good view of the planet's north pole," says West. "At first there was nothing unusual--just ordinary polar clouds. Then the Dark Spot emerged." For weeks Cassini's UV-sensitive cameras watched as the cloud grew into an oval the size of the Great Red Spot itself. It swirled, darkened and changed shape until, as Cassini was departing, it began to fade again. (See the movie.)

"The Dark Spot is ephemeral," says West. That's probably why Hubble saw it only once. And if Cassini had arrived a month or two later, it might not
have seen the Dark Spot at all. Instead, Cassini's cameras monitored the
cloud for 11 straight weeks, and those data have allowed West to draw some conclusions:

The Great Dark Spot and the Great Red Spot are entirely different," he says. The Great Red Spot is deep. "It's a high-pressure storm system rooted in Jupiter's troposphere far below the cloudtops. The Great Dark Spot is apparently shallow and confined to Jupiter's high stratosphere."

West believes the Dark Spot is a curious side-effect of auroras on Jupiter.

"Jupiter has Northern Lights just as Earth does, although on Jupiter they
are hundreds to thousands of times more powerful," says West. Auroras happen when electrons and ions rain down on the polar atmosphere and cause the air to glow where they hit. Here on Earth, auroras are usually sparked by solar wind gusts. The solar wind can also trigger auroras on Jupiter, but it's not necessary: On Jupiter, the planet itself energizes Northern Lights. "Jupiter's magnetic field is a huge reservoir of charged particles," explains West. "These particles are accelerated poleward by the 11-hour rotation of Jupiter and its magnetic field. Thus, auroras on Jupiter are almost always active."

. . . Indeed, the Great Dark Spot is invisible to the human eye. "It can only be seen in UV light."

. . . What caused it to appear when Cassini was flying by? We don't know. This shows us that Jupiter's stratosphere is a more interesting place than we once thought."

Furthermore, it can teach us something about our own planet.

West explains: "This dark spot is trapped by a polar vortex--a jet stream
that encircles Jupiter's north pole." Fast-moving winds in the vortex act
like an atmospheric wall, keeping the Dark Spot corralled at high latitudes.
Similar vortices encircle Earth's polar regions. Our planet's Arctic vortex
is disrupted somewhat by northern land masses, but the Antarctic vortex is
better organized. It plays a key role in confining the ozone hole--much as
Jupiter's polar vortex confines the Great Dark Spot.

"Monitoring the Dark Spot could help us understand how planetary vortices
work." For such studies, two planets are clearly better than one.

The picture of northern lights on Jupiter is amazing, BTW.

Great stuff Larry!

Larry you asked me back in March whether or not the public could look through the telescopes on Mauna Kea - At the 10,000 foot level there are telescopes for stargazing. There are no telescopes at the top - it is all electronic devises scanning the universe.

I thought there were telescopes at the top, but a friend of mine who is the chef at the observatory set me straight.

Sglass