Astronomy Picture Of the Day (APOD)The Dotted Dunes of Mars
What causes the black dots on dunes on Mars? As spring dawns on the Northern Hemisphere of Mars, dunes of sand near the poles being to defrost. Thinner regions of ice typically thaw first revealing sand whose darkness soaks in sunlight and accelerates the thaw.
APOD: 2004 August 30- Announcing Comet C 2003 K4 LINEAR
A comet discovered last year has brightened unexpectedly and now may become visible to the unaided eye within the next month. Designated Comet C/2003 K4 (LINEAR), the comet was discovered in 2003 May by project LINEAR.
Our Moon's appearance changes nightly. This time-lapse sequence shows what our Moon looks like during a lunation, a complete lunar cycle. As the Moon orbits the Earth, the half illuminated by the Sun first becomes increasingly visible, then decreasingly visible. The Moon always keeps the same face toward the Earth.
APOD: 2004 August 28- M17: A Hubble Close-Up
Sculpted by stellar winds and radiation, these fantastic, undulating shapes lie within the stellar nursery known as M17, the Omega Nebula, some 5,500 light-years away in the nebula-rich constellation Sagittarius. The lumpy features...
APOD: 2004 August 27- The Sedna Scenario
The discovery of Sedna (aka 2003 VB12), the most distant known object orbiting the Sun, presents a mystery. Pluto's orbit averages about 40 AU in radius, where an AU (Astronomical Unit) is the Earth-Sun distance.
APOD: 2004 August 26- Cassiopeia A in a Million
One million seconds of x-ray image data were used to construct this view of supernova remnant Cassiopeia A, the expanding debris cloud from a stellar explosion. The stunningly detailed image from the Chandra Observatory will allow an unprecedented exploration of the catastrophic fate that awaits stars much more massive than the Sun.
Zodiacal Light and the False Dawn
An unusual triangle of light will be particularly bright near the eastern horizon before sunrise during the next two months for observers in Earth's northern hemisphere. Once considered a false dawn, this triangle of light is actually Zodiacal Light, light reflected from interplanetary dust particles.
APOD: 2004 August 24- Supply Ship Approaches the Space Station
The crew on board the International Space Station sometimes needs supplies. As the US Space Shuttle fleet prepares to return to flight, supplies usually now come from a robot Progress supply vessel launched from Kazakhstan.
Looking Out Over Mars
What would it be like to climb a hill and look out over Mars? That opportunity was afforded the Spirit rover earlier this month as it rolled to a high perch in the Columbia Hills.
Earth at Night
This is what the Earth looks like at night. Can you find your favorite country or city? Surprisingly, city lights make this task quite possible. Human-made lights highlight particularly developed or populated areas of the Earth's surface, including the seaboards of Europe, the eastern United States, and Japan.