Astronomy

Last night I had a chance to see Raduga 33, my first Iridium flare : right on the predicted time and location, it lit up. Iridium flares are small communications satellites providing spectacular visible reflective flares/glints to observers on the ground. With only a normal brightness of +6 magnitude, occasionally some of the Iridium satellites provide reflective flares of magnitude -8. For comparison, Venus can be as bright as magnitude -4.9, thus reflections can be up to 30 times brighter than Venus. The flares can last anywhere from 5 to 20 seconds before the satellite once again becomes almost invisible to the naked eye.

Heavens Above is a true gold mine for satellite spotters. Its aim is to provide you with all the information you need to observe satellites such as the International Space Station and the Space Shuttle, spectacular events such as the dazzlingly bright flares from Iridium satellites by offering you detailled information and star charts.

Giotto and the Halley comet. Comet Shoemaker-Levy 9 hits Jupiter. Mars Pathfinder.
Astrobio has a wonderfull timeline of what important things have happened lately in astronomy and space exploration. For some a collection of wonderfull memories, for others a valuable update of the important astronomical events in the last 25 years.

*The* astronomical event of 2003 is the Mars opposition of August. That month, Mars has never been so close to Earth in the last 20 years. One good reason to send a load of Mars robots to the red planet, but also to observe Mars from a telescope. If you really want to know what you're going to see through your telescope, Mars Previewer II may be of interest : it's a Windows program which was distributed with a copy of Sky and Telescope, and shows you the current visible details of the red planet. I didn't managed to get it running under Wine, so for the Linux and Mac OSX folks, the next link may be of interest : this site simulates the rotation of Mars, so you''ll have a good impression of the possible visible details.
In 2001, NASA launched the Mars Odyssey, to map the Mars surface. The result is depicted on the Themis site, with high detailled pictures of our neighbour planet; 1 pixel equals 20 meters. The climax on the site though is this magnificent inzoomable Mars chart.

The past month stirred up the astronomy feeling again, even up to the point that I'm considering the purchase of a bigger telescope (a 8 or 10 inch Dobson seems nice). The etching databases of Regulus and Dog Star are nice impressions of what is possible with those big scopes.

NASA has an impressive solar system simulator, where you can see any planet from any point in space. Though it looks a lot like some Celestia screenshots...

KStars is getting better with every release. Originally intended as an educational planetarium program, it now includes stars up to magnitude 7 or 8, which makes it already usable as a star atlas for owners of a small sized telescope.

However, if you want to make real deep sky observations, magnitude 8 is just not detailled enough. And that's the only drawback of KStars; you can add different star catalogi, but there are no detailed ones available. For "professional" use, XEphem is the real pogram to use. I discovered this page, where the Tycho2 and Hipparcos catalogi for use with XEphem can be downloaded. It provides you a star atlas with 2 400 000 stars up to magnitude 13.

The Pioneer 10 spacecraft has sent its last signal to Earth. Pioneer's last, very weak signal was
received on Jan. 22, 2003. NASA engineers report Pioneer 10's
radioisotope power source has decayed, and it may not have enough power to send additional transmissions to Earth.

"Originally designed for a 21-month mission, Pioneer 10 lasted more than 30 years. It was a workhorse that far exceeded its warranty, and I guess you could say we got our money's worth," said Pioneer 10 Project Manager, Dr. Larry Lasher.

Pioneer 10 was launched March 2, 1972 for a flight to Jupiter, making it the fastest human-made object to leave the Earth; fast enough to pass the moon in 11 hours and to cross Mars' orbit, about 50 million miles away, in just 12 weeks. Pioneer 10 was the first spacecraft to pass through the asteroid belt, considered a spectacular achievement, and then headed toward Jupiter. In 1983, Pioneer 10 became the first human-made object to pass the orbit of Pluto, the most distant planet from the Sun.
Following its encounter with Jupiter, Pioneer 10 explored the outer regions of the solar system, studying energetic particles from the Sun (solar wind), and cosmic rays entering our portion of the Milky Way. The spacecraft continued to make valuable scientific investigations in the outer regions of the solar system until its science mission ended March 31, 1997.

Pioneer carries human greetings in the form of a gold anodized plaque with symbolic drawings, an attemp of the NASA engineers to send out a
human greeting card into outer space. Carl Sagan designed the plaque to be universally (in the truest sense) comprehensible, at least to any civilization sufficiently advanced to capture it. However, it will probably be mankind itself which will bring the spacecraft home, as we probably will encounter Pioneer in the future during high speed space
travel.

Nice pictures viewed from any satellite around Earth.

SETI is a scientific project using large telescopes in the search for extra-terrestrial intelligence. On August 15, 1977 the Ohio State Radio Observatory detected the most promising extraterrestrial candidate signal to date. The so-called "Wow!" signal received its name from the note written in the margin of the computer printout by Dr. Jerry Ehman. The signal rises about 15 dB above the mean background noise, in a single channel.

An analysis of the Wow! signal indicates that its source was moving with the background stars. From its Doppler shift signature, terrestrial interference, aircraft, and spacecraft can be ruled out as possible origins of the signal. The antenna coordinates indicated that the signal was coming from no known nearby solar-type stars. The only condition required for a SETI signal not met was that of repeatability. However, since the Ohio State Big Ear radiotelescope has an extremely narror beamwidth, viewing just one part in a million of the sky at any given time, one would not expect the signal to repeat. Assuming the Wow! signal is a typical SETI-like transmission, then we can expect valid SETI hits to be very strong, high intermittent signals which appear once (as the transit beam sweeps past Earth), and never repeat again. Unless the signal is detected again, we may never know for sure.

If you took a picture of the Sun at the same time each day, would it remain in the same position? The answer is no, and the shape traced out by the Sun over the course of a year is called an analemma. The Sun's apparent shift is caused by the Earth's motion around the Sun when combined with the tilt of the Earth's rotation axis. The Sun will appear at its highest point of the analemma during summer and at its lowest during winter.