MARS: NASA's Dawn
spacecraft had a close encounter with Mars last night, flying
just 341 miles above the Red Planet's surface. The gravity-assist
maneuver propelled Dawn toward the asteroid belt where it will orbit
and explore Vesta
and Ceres beginning in 2011. Mission managers say the Mars flyby
images will be beamed back to Earth on or about Feb. 24th.
COMET LULIN UPDATE:
Last week, observers saw little of Comet
Lulin because it was lost in the glare of the passing Moon. The
glare is subsiding now and Lulin is back--better than ever. Observers
say it is visible to the naked-eye (magnitude +5.6) as a faint gassy
patch in the constellation Virgo before dawn. Backyard telescopes
reveal a full-fledged comet, vivid green, that moves as you watch
it. On Feb 17th, Joe Gafford of Deer Trail, Colorado, caught a solar
wind gust tearing away part of Comet Lulin's tail:
The view will improve in the nights ahead. Comet Lulin is approaching
Earth for a 38-million-mile close encounter on Feb. 24th. At
that time, the comet could shine two or three times brighter than
it does now, and photographers will record it using cameras alone--no
telescope required. Browse the gallery for a hint of things to come:
Lulin Photo Gallery
Hunter Telescope] [Sky maps: Feb.
More than a week has passed since the Feb.
10th collision of Iridium 33 and Kosmos 2251 over northern Siberia,
and the orbits of some of the fragments have now been measured by
US Strategic Command. Orbital elements are available for 8 pieces
of debris from Iridium 33 and 18 pieces from Kosmos 2251. Satellite
observer Daniel Deak has plotted those orbits on a 3D map of Earth
for readers of Spaceweather.com. Click on the image to view the
distribution of Iridium debris on Feb. 18th:
A similar map
highlights the Kosmos debris, and a polar
view is available, too.
In the maps, hollow circles denote primary fragments still being
tracked with the same catalogue number as the original satellite.
"We can say it is what remains of the satellite after the collision,"
explains Deak. Solid circles denote lesser fragments; they are scattered
almost all the way around Earth.
A comparison of Kosmos
vs. Iridium maps shows that Kosmos debris is scattered more
widely than Iridium debris in orbital phase, eccentricity and inclination.
For some reason, Kosmos fragments seem to have been ejected from
the crash with a greater velocity than Iridium counterparts.
This is just the beginning. More fragments, perhaps hundreds of
them, will be catalogued in the days and weeks ahead. As they are
added to the map, new information about the crash and its aftermath
will naturally emerge. Stay tuned!
2009 Aurora Gallery
[Previous Februaries: 2008,
the Sunspot Cycle