VANISHING MOONS OF
JUPITER: Tonight, Sept. 2nd-3rd, for the
first time in many years, the moons of Jupiter are going to disappear.
At least that's how it will seem when Io, Europa, Ganymede and Callisto
line up in front of and behind the giant planet. A casual look through
a backyard telescope will show no moons at all. The 2-hour vanishing
act begins at 9:43 p.m PDT. Jupiter is easy to find right beside
the nearly full Moon. [sky
On Sept. 2nd, a billion-ton coronal mass
ejection (CME) slammed into Earth's magnetic field. Campers in the
Rocky Mountains woke up in the middle of the night, thinking that
the glow they saw was sunrise. No, it was the Northern Lights. People
in Cuba read their morning paper by the red illumination of aurora
borealis. Earth was peppered by particles so energetic, they altered
the chemistry of polar ice.
Hard to believe? It really happened--exactly 150 years ago. This
map shows where auroras were sighted in the early hours of Sept.
Above: Aurora sightings, Sept. 2,
1859. Image courtesy J.L. Green, NASA
As the day unfolded, the gathering storm electrified
telegraph lines, shocking technicians and setting their telegraph
papers on fire. The "Victorian Internet" was knocked offline.
Magnetometers around the world recorded strong disturbances in the
planetary magnetic field for more than a week.
The cause of all this was an extraordinary
solar flare witnessed the day before by British astronomer Richard
Carrington. His sighting marked the discovery of solar flares and
foreshadowed a new field of study: space weather. According to the
National Academy of Sciences, if a similar flare occurred today,
it would cause $1 to 2 trillion in damage to society's high-tech
infrastructure and require four to ten years for complete recovery.
A repeat of the Carrington Event seems unlikely from
our low vantage in a deep solar minimum--but don't let the quiet
fool you. Strong flares can occur even during weak solar cycles.
Indeed, the Carrington flare itself occured during a relatively
weak cycle similar to the one expected to peak in 2012-2013.
Could it happen again? Let's
2009 Aurora Gallery
[previous Augusts: 2008,
Space shuttle Discovery is docked to the International Space Station
(ISS) and together the two spaceships are putting on a good show
in the night sky. Peter Rosén caught them flying over Stockholm,
Sweden, just before sunrise on August 31st:
"The mission is getting a lot of media coverage here because
of our Swedish astronaut Christer Fuglesang," says Rosén.
On Monday,Fuglesang helped unload more than 15,000 lb (Earth weight)
of supplies from Discovery's cargo bay. Much of that weight was
laboratory equipment. Astronauts are outfitting the space station's
science labs with a -80 degree research freezer; a rack of hardware
to study crystals and semiconductors in low gravity; and a new set
of tools for microgravity fluid physics experiments. NASA says this
mission marks an important transition. The space station's "Under
Construction" sign is coming down and its world-class science
labs are ramping up.
That's worth a look. Check the Simple
Satellite Tracker for flybys.
the Sunspot Cycle