Astronomy Picture of the Day 6-21-03

NASA ^ | 6-21-03 | Robert Nemiroff and Jerry Bonnell

[petuniasevan]

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2003 June 21

A Crescent Earth at Midnight
Credit: GOES Project, GSFC, NASA

Explanation: The Earth's northern hemisphere is outlined as a sunlit crescent in this dramatic view from orbit, recorded near local midnight by the Geostationary Operational Environmental Satellite (GOES-8) on June 22, 1996. That date was two days after the Solstice, by astronomical reckoning, the first day of summer in the north and winter in the southern hemisphere. Today's scheduled geocentric astronomical event is again the northern hemisphere's summer Solstice, with the Sun reaching its northernmost declination at 19 hours 10 minutes Universal Time. That makes today also the longest day of the year in the north, with the arctic regions near the top of the picture experiencing 24 hours of daylight. Looking south along the Earth's limb, atmospheric scattering of sunlight causes the limb to be visible beyond areas directly illuminated by the sun.

[petuniasevan]

"Solstice" means "sun stands still"; it appears to rise, transit and set in the same place at the same time for several days.

How long does darkness last on this the shortest night of the year in the Northern Hemisphere? It depends on your location. If you are far enough north, it stays light all night.

Here in Wisconsin (44 degrees north) the twilight ended around 10:45 PM and will return at about 3 AM. On the other hand, in a more southerly location such as Dallas the night will last longer. Twilight there ends at about 10:10 PM and returns at about 4:45 AM.

Farther north in Anchorage, the sun sets at local time 11:15 PM and twilight lasts until it rises again at 4:35 AM.

[petuniasevan]

[Graewoulf]

I'm told that the maximum relief on the Earth's surface is similar, in scale, to the relief on an orange.

[firewalk]

Thanks for the thread
& the ping

[RightWhale]

At Prudhoe Bay the sun has been up for a month. It just goes around and around.