Astronomy Picture Of the Day (APOD)The Outer Shells of Centaurus A
What causes the surrounding shells in peculiar galaxy Cen A? Last month a fascinating image of peculiar galaxy Centaurus A was released, processed to highlight a faint blue arc indicating an ongoing collision with a smaller galaxy.
A Green Flash from the Sun
Many think it is just a myth. Others think it is true but its cause isn't known. Adventurers pride themselves on having seen it. It's a green flash from the Sun. The truth is the green flash does exist and its cause is well understood.
A Cerro Tololo Sky
High atop a Chilean mountain lies one of the premier observatories of the southern sky: the Cerro Tololo Inter-American Observatory (CTIO). Pictured above is the dome surrounding one of the site's best known instruments, the 4-meter Blanco Telescope.
NGC 6369: The Little Ghost Nebula
This pretty planetary nebula, cataloged as NGC 6369, was discovered by 18th century astronomer William Herschel as he used a telescope to explore the constellation Ophiucus. Round and planet-shaped, the nebula is also relatively faint and has acquired the popular moniker of Little Ghost Nebula.
2001 Leonids: Meteors in Perspective
The 2001 Leonid storm was so intense that the meteor shower's radiant, the point on the sky from which the fleeting trails seemed to diverge, was easy to spot. But the bits of debris that created the meteors really moved along parallel paths, following the orbit of their parent comet Tempel-Tuttle.
The Winter Hexagon
Some of the brightest stars form a large and easily found pattern in the winter sky of Earth's northern hemisphere. Dubbed the Winter Hexagon, the stars involved can usually be identified even in the bright night skies of a big city.
Leonids Over Joshua Tree National Park
This year's Leonid Meteor Shower is predicted to have two peaks, like last year's. The first peak should come at about 04:00 hours Universal Time (UT) on November 19 and be primarily visible from Western Europe before sunrise.
Cassini Approaches Saturn
Cassini, a robot spacecraft launched in 1997 by NASA, is close enough now to resolve many rings and moons of its destination planet: Saturn. The spacecraft has closed to about two Earth-Sun separations from the ringed giant. Last month, Cassini snapped several images during an engineering test.
The International Space Station Expands Again
The developing International Space Station (ISS) has changed its appearance yet again. Last month the Space Shuttle Atlantis visited the ISS and installed the third of eleven pieces that will compose the Integrated Truss Structure. The new S-1 Truss is visible on the right, below the extended solar panels across the top.
NGC 604: Giant Stellar Nursery
Scattered within this cavernous nebula, cataloged as NGC 604, are over 200 newly formed hot, massive, stars. At 1,500 light-years across, this expansive cloud of interstellar gas and dust is effectively a giant stellar nursery located some three million light-years distant in the spiral galaxy, M33.