Astronomy Picture Of the Day (APOD)M42: Orion Nebula Mosaic
The Great Nebula in Orion is one of the most interesting of all astronomical nebulae known. Here fifteen pictures from the Hubble Space Telescope have been merged to show the great expanse and diverse nature of the nebula.
At the Core of M15
Densely packed stars in the core of the globular cluster M15 are shown in this Hubble Space Telescope (HST) image taken in April of 1994. The stars revealed are contained in an area 1.6 light years across and their colors roughly indicate their temperatures - hot stars appear blue, cooler stars look reddish-orange.
New York at Night
This tantalizingly clear photo of New York City at night was taken by the astronauts during the Space Radar Laboratory mission of the Space Shuttle Endeavor in March of 1990. In this view, oriented with East up and North to the left, a dense constellation of lights defines the major metropolitan areas.
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.