Astronomy Picture Of the Day (APOD)Water World
Water (Dihydrogen Oxide, H2O) is a truly remarkable chemical compound and is fundamental to life on Earth. Earth is the only planet in the Solar System where the surface temperature and pressure allow the three forms of water, solid (ice), liquid (ocean), and gas (water vapor condensing in clouds) to exist simultaneously on its surface.
The Sun Also Rises
Sunrise seen from low Earth orbit by the shuttle astronauts can be very dramatic indeed (and the authors apologize to Hemingway for using his title!). In this breathtaking view, the Sun is just visible...
The first Hubble Space Telescope (HST) servicing mission, STS-61, was one of the most complicated shuttle missions ever planned. Launched on December 2, 1993 in the Space Shuttle Endeavor, the astronauts were required to make 5 space walks to repair the HST. Astronaut F.
A Quintet of Galaxies
Five closely grouped galaxies are visible in this image made using the Kitt Peak National Observatory 2.1 meter telescope. The grouping is commonly known as Stephan's Quintet. Four of the galaxies show essentially the same redshift suggesting that they are at the same distance from us.
Aurora and Orion
Looking toward the south from low Earth orbit, the crew of the Space Shuttle Endeavor made this stunning time exposure of the Aurora Australis (southern lights) in April of 1994. The aurora are caused by high energy electrons from the Solar Wind which are funneled into the atmosphere by the Earth's magnetic field.
Virgo Cluster Galaxies
Pictured are several galaxies of the Virgo Cluster, the closest cluster of galaxies to the Milky Way. The Virgo Cluster spans more than 5 degrees on the sky - about 10 times the angle made by a full Moon. It contains over 100 galaxies of many types - including spirals, ellipticals, and irregular galaxies.
Blue Jet Lightning
Recently two new types of lightning have been verified: red sprites and blue jets. These atmospheric discharges occur very high in the Earth's atmosphere - much higher than the familiar form of lightning. Blue jets appear blue in color and go from the tops of clouds to a height of about 50 kilometers.
Red Sprite Lightning
Recently two new types of lightning have been verified: red sprites and blue jets. These atmospheric discharges occur very high in the Earth's atmosphere - much higher than the familiar form of lightning.
Lightning and the Space Shuttle
There are many things about lightning that are not understood. Lightning has been seen in the atmospheres of Venus, Earth, Jupiter, and Saturn. A leading theory is that collisions of particles in clouds cause large areas of positive and negative charge.
M104: The Sombrero Galaxy
The famous Sombrero galaxy (M104) is a bright nearby spiral galaxy. The prominent dust lane and halo of stars and globular clusters give this galaxy its name. Something very energetic is going on in the Sombrero's center, as much X-ray light has been detected from it.