Eclipse season begins for WISE
Halfway Around
April 10, 2010JPL Open House
May 18, 2010
The Sun has now moved far enough North that WISE is being eclipsed when it passes over the South Pole. The orbit of WISE is inclined by 97.5 degrees, and the end of the orbit normal that is close to the Sun in the sky is at -7.5 degree declination. The Sun has now reached 15 degrees declination, so when WISE is over the South pole the elevation of the Sun is -22.5 degrees. But the horizon is depressed by 22.6 degrees at the elevation of WISE, so the Sun is now partially eclipsed over the poles. Within a day or two WISE will be experiencing total eclipses once per orbit.
nwright
Ned Wright, 65 years old, is a professor at UCLA. He did far-infrared observations using a 102-cm balloon-borne telescope for his PhD thesis, and has since observed with the Kuiper Airborne Observatory, and the space-based COBE, WMAP, Spitzer and WISE missions.
2 Comments
Thanks for the update, Dr. Wright.
I’m curious – do the eclipses that WISE encounters lead to thermal cycling effects that must be compensated for in the returned results? Or was all that taken care of in the spacecraft’s original design?
-Tom
WISE was designed for the eclipse season. The solar panels are big enough to recharge the battery between eclipses. The scientific instrument is chilled by frozen hydrogen and has a very steady temperature.