1. Astronomy Picture of the Day (2007 Sep. 24)
Explanation: How do stars form? To help study this complex issue, astronomers took a deep image in infrared light of an active part of our Milky Way Galaxy where star formation is rampant. In IRDC G , thick clouds of dust and gas are congealing into stars that are so dark that humans living there would see an empty night sky. The image, though, taken last year by the Spitzer Space Telescope in infrared light, shows vast glowing fields of gas and dust, indicating that much of this dust is heated by forming stars. The centers of some clouds, such as the snake-like structure on the upper left, are so thick and cold that they are dark even in infrared light. Many of the red dots are glowing dust shrouds centered on very young newly formed stars. The unusual red sphere below the snake is actually a supernova remnant, the glowing shell of a young star so massive it evolved rapidly and exploded. The region spans about 150 light years and lies about 10,000 light years away toward the constellation of Sagittarius
A Galactic Star Forming Region in Infrared

2. Astronomy Picture of the Day (2007 Sep. 24)
The Sun crossed the celestial equator heading south at 0951 UT, Sep. 23, 2007.
Explanation: How do stars form? To help study this complex issue, astronomers took a deep image in infrared light of an active part of our Milky Way Galaxy where star formation is rampant. In IRDC G , thick clouds of dust and gas are congealing into stars that are so dark that humans living there would see an empty night sky. The image, though, taken last year by the Spitzer Space Telescope in infrared light, shows vast glowing fields of gas and dust, indicating that much of this dust is heated by forming stars. The centers of some clouds, such as the snake-like structure on the upper left, are so thick and cold that they are dark even in infrared light. Many of the red dots are glowing dust shrouds centered on very young newly formed stars. The unusual red sphere below the snake is actually a supernova remnant, the glowing shell of a young star so massive it evolved rapidly and exploded. The region spans about 150 light years and lies about 10,000 light years away toward the constellation of Sagittarius
A Galactic Star Forming Region in Infrared

3. Peru Meteor Crash (Sep. 16, 2007)

4. Advanced Question Chap. 3, Q31 in P61
The Moon moves noticeably on the celestial sphere over the space of a single night. To show this, calculate how long it takes the Moon to move through an angle equal to its own angular diameter (0.5 deg) against the background of stars. Give your answer in hours.
(b) Through what angles (in degrees) does the Moon move during a 12-hour night? Can you notice an angle of this size?

5. Advanced Question Chap. 3, Q31 in P61
Answer:
(1) The sidereal period of the moon is 27.3 days, which takes the moon move 360 deg.
For moving 0.5 deg
T (hrs) = 0.5 (deg) X 27.3 (day) X 24.0 (hr)/(day) / 360 (deg)
= 0.91 hours
(2) In a 12 hour period,
A (deg) = 12 (hr) X 0.5 (deg) / 0.91 (hr) = 6.6 (deg).
This angle is greater than the seperation of the pointer stars in Big Dipper and is certainly noticeable,