The Coma Cluster of Galaxies

The Coma Cluster of Galaxies



Almost every object in the above photograph is a galaxy. The Coma Cluster of Galaxies pictured above is one of the densest clusters known - it contains thousands of galaxies. Each of these galaxies houses billions of stars - just as our own Milky Way Galaxy does. Although nearby when compared to most other clusters, light from the Coma Cluster still takes hundreds of millions of years to reach us. In fact, the Coma Cluster is so big it takes light millions of years just to go from one side to the other! Most galaxies in Coma and other clusters are ellipticals, while most galaxies outside of clusters are spirals. The nature of Coma's X-ray emission is still being investigated.

Moonrise Over Seattle

Moonrise Over Seattle



Is the Moon larger when near the horizon? No -- as shown above, the Moon appears to be very nearly the same size no matter its location on the sky. Oddly, the cause or causes for the common MoonIllusion are still being debated.Two leading explanations both hinge on the illusionthat foreground objects make a horizon Moon seem farther in the distance. The historically mostpopular explanation then holds that the mind interprets more distant objects as wider, while a morerecent explanation adds that the distance illusion may actually make the eye focus differently. Either way, the angulardiameter of the Moon is always about 0.5 degrees. In the above time-lapse sequence taken near the end of 2001, the Moon was briefly re-imaged every 2.5 minutes, with the last exposure of longer duration to bring up a magnificent panorama of the city of Seattle.

Peculiar Arp 295

Peculiar Arp 295



A spectacular bridge o starsand gas stretchesfor nearly 250,000 light-years and joins this famou peculiarpair of galaxies cataloge as Arp 295.The cosmic bridge between th galaxies and the long tail extendingbelow and right of picture center are strong evidencethat these two immense star systems hav passed close to each otherin the past, allowing violent tides induced by mutual gravityto create th eye-catching plumes of stellar material.Whil suchinteractions are drawn out overbillions of years, repeate closepassages should ultimately result inthe merger of this pair of galaxies into a larger singlegalaxy of stars.Althoug thisscenario does look peculiar, galactic mergers are thoughtto be common, with Arp 295 representing an early stage ofthis inevitable process.The Arp 295 pair are the largest of a loose grouping ofgalaxies about 270 millionlight-years distant toward the constellation Aquarius.This deep color imageof the region was recorded in September using the USN 1 metertelescope near Flagstaff, Arizona.

Radio Jupiter

Radio Jupiter



Thisview of ga giant Jupiter,made from data recorded at the VeryLarge Array radio observatory near Socorro, New Mexico,may not look too familiar.In fact, there is no sign of a bright, round planet striped withcloud bands, sporting Great Red Spot.Instead, th radiowaves mapped in this false-color imageare produced by energetic electrons trapped withinJupiter's intens magneticfield.The radio emitting region extends far beyond Jupiter's cloud tops,to over twice the visible radius of the planet,and surrounds Jupiter like an oversized version ofEarth's Van Allen radiation belt.While it glows strongly at radio wavelengths, Jupiter' radiationbelt is invisible in the more familia optical an infrared viewswhich show the Jovian cloud tops and atmospheric features inreflected sunlight.

The Sombrero Galaxy from HST

The Sombrero Galaxy from HST



Why does the Sombrero Galaxy look like a hat? Reasons include the Sombrero's unusually large and extended central bulge of stars, and dark prominent dust lanes that appear in a disk that we see nearly edge-on. Billions of old stars cause the diffuse glow of the extended central bulge. Close inspection of the bulge in the above photograph shows many points of light that are actually globular clusters M104's spectacular dust rings harbor many younger and brighter stars, and show intricate details astronomers don't yet fully understand. The very center of the Sombrero glows across the electromagnetic spectrum, and is thought to house a large black hole. Fifty million-year-old light from the Sombrero Galaxy can be seen with a small telescope towards the constellation of Virgo.

The Colorful Horsehead Nebula

The Colorful Horsehead Nebula



While drifting through the cosmos, a magnificent interstellar dust cloud became sculpted by stellar winds and radiation to assume a recognizable shape. Fittingly named the Horsehead Nebula, it is embedded in the vast and complex Orion Nebula. The dark molecular cloud, roughly 1,500 light years distant, is cataloged as Barnard 33 and is visible only because its obscuring dust is silhouetted against the bright emission nebula IC 434. The bright blue reflection nebula NGC 2023 is visible on the lower left. The prominent horse head portion of the nebula is really just part of a larger cloud of dust which can be seen extending toward the bottom of the picture. A potentially rewarding but difficult object to view with a small telescope, this gorgeous representative-color image was taken by the large 3.6-m Canada-France-Hawaii Telescope in Hawaii, USA.

A Near Record Ozone Hole in 2003

A Near Record Ozone Hole in 2003



As expected, the ozone hole near Earth's South Pole is back again this year.This year's hole, being slightly larger than North America, is larger than last year but short of the record set on 2000 September 10 Ozone is important because it shields us from damaging ultraviolet sunlight. Ozone is vulnerable, though, to CFCs and halons being released into the atmosphere. Inte national efforts to reduce the use of these damaging chemicals appear to be having a positive effect on their atmospheric abundance. The relatively large size of the ozone hole this year, however, is attributed partly to colder than normal air in the surrounding stratosphere. The above picture of the ozone hole was taken on September 11 by TOMS on board the orbiting Earth Probe satellite.

Apollo 12 Visits Surveyor 3

Apollo 12 Visits Surveyor 3



Apollo 12 was the second mission to land humans on the Moon.The landing site was picked to be near the location of Surveyor 3, a robot spacecraft that had landed on the Moon three years earlier.In the above photograph, taken by lunar module pilo Alan Bean,mission commander Pete Conrad jiggles the Surveyor spacecraft to see how firmly it is situated.The lunar module is visible in the distance. Apollo 12brought back many photographs and moon rocks. Among the milestones achieved byApollo 12 was the deployment of the Apollo Lunar Surface Experiments Package, which carried out many experiments including one that measured the solar wind.