Space.com

What's Hot This Week Earth's Seasons Change With Equinox by Mike Wall, SPACE.com Senior Writer Bad news for Northern Hemisphere dwellers: summer is officially over. Earth's seasons changed Friday at 5:05 a.m. EDT (0905 GMT) with the arrival of the September equinox. See Mars Near the Moon by Joe Rao, SPACE.com Skywatching Columnist On Friday, Sept. 23, the sun will cross the celestial equator, heading south, in the annual equinox marking the start of the fall season in the Northern Hemisphere and the spring in the south. But this year's equinox brings a special treat: the moon and planet Mars shining together at dawn. Sponsored by: Apollo Astronauts to Congress: Bring Back the Space Shuttle The Curious Case of Comet Elenin: A Weird Skywatching Tale 10 Real Alien Worlds That Resemble 'Star Wars' Planets 20 Most Marvelous Moon Missions The Top 10 Star Trek Technologies