Astronomy Picture of the Day

Discover the cosmos!Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2008 April 27

The Galactic Center Radio Arc
Credit: Farhad Zadeh et al. (Northwestern), VLA, NRAOWhat causes this unusual structure near the center of our Galaxy?The long parallel rays slanting across the top of the above radio image are known collectively as the Galactic Center Radio Arc and jut straight out from the Galactic plane. The Radio Arc is connected to the Galactic centerby strange curving filaments known as the Arches. The bright radio structure at the bottom right likely surrounds a black hole at theGalactic center and is known as Sagittarius A*. One origin hypothesis holds that the Radio Arc and the Arches have their geometry because they contain hot plasma flowing along lines of constant magnetic field. Images from the Chandra X-ray Observatoryappear to show this plasma colliding with a nearby cloud of cold gas.bright steps

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This Envisat image features the southeastern part of the Russian Federation, the northeastern tip of the People’s Republic of China, the Amur and Ussuri Rivers, the Sikhote-Alin Mountain Range, the Sea of Japan and Sakhalin Island.

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Reuters – Images of colliding galaxies show them spinning, sliding and slipping into one another, wreaking stellar destruction that will give birth to new and larger galaxies.

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2008 April 25 M86 in the Virgo Cluster Greg Morgan(SierraRemote Observatories)Brightlenticulargalaxy M86 is near center of this cosmic view,at the heart of theVirgo GalaxyCluster.Other bright galaxies in the neighborhoodinclude M84at the upper right,edge-on spiral NGC4388 near the right edge,a striking pair of interacting galaxies,Markarian’s Eyes,in the lower left corner,and edge-on spiral NGC 4402 at about 11 o’clock.With well over a thousand members, theVirgo Cluster is theclosest largecluster of galaxies.On average the cluster galaxies are measured to be about50 million light-years away.The entireVirgo Cluster is difficult to appreciatebecause it covers such a large area, spanning over 10 degreeson the sky.This cluster close-upcovers a region just under 1 degree wide or about 1.5 times the sizeof the full moon.the zone

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ESA’s Jules Verne ATV was used for the first time early this morning to raise the orbit of the International Space Station. A 740-second burn of the Automated Transfer Vehicle’s main engines successfully lifted the altitude of the 280-tonne Station by around 4.5 km to a height of 342 km above the Earth’s surface.

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AFP – An Indian rocket will next week launch an advanced remote-sensing satellite that will help plan and implement urban and rural development projects, the space agency said Thursday.

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2008 April 26 The Tarantula Zone Robert GendlerTheTarantula Nebula is more than 1,000 light-years in diameter –a giant star forming region within our neighboring galaxythe Large Magellanic Cloud (LMC).That cosmic arachnid lies at the upper left ofthisexpansive mosiac covering a part of the LMCover 6,000 light-years across.Within the Tarantula (NGC 2070), intense radiation, stellar winds andsupernova shocks from the central young cluster of massivestars, cataloged as R136,energize the nebular glow and shape the spidery filaments.Around the Tarantula are other violent star-forming regions withyoung star clusters, filaments andbubble-shaped clouds.The small but expanding remnant ofsupernova 1987a, the closest supernovain modern history, is located near the center of the view.The rich field is about as wideas four full moons on the sky, located in the southernconstellationDorado.on the radio

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SPACE.com – A motorglitch has resurfaced aboard NASA’s Mars rover Opportunity and may hinder someof the long-lived robot’s ability to wield its mechanical arm.

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The High Resolution Stereo Camera on board ESA’s Mars Express orbiter imaged the region of Nepenthes Mensae, a river delta on Mars, on 22 January 2008. The region is located in the eastern hemisphere of Mars, close to the boundary between the northern lowlands and the southern highlands.

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2008 April 24 Cygnus Without Stars Igor ChekalinThe sky is full of hydrogen, though it can take asensitive camera and telescope to see it.For example, this twelve-degree-wide view of thenorthern partof the constellationCygnusreveals cosmic clouds ofhydrogen gasalong the planeof our Milky Way galaxy.The mosaic oftelescopic images was recorded through anh-alpha filter that transmits only visible red light fromglowing hydrogen atoms.Further digital processing has removed most of what is leftof the myriad, point-like Milky Way stars from the scene, thoughbright Deneb, alpha star ofCygnus and head of the Northern Cross, remains near top center.Recognizable bright nebulae includeNGC 7000 (North America Nebula), andIC 5070 (Pelican Nebula) at the upper left withIC 1318 (Butterfly Nebula) andNGC 6888 (Crescent Nebula) at lower right –but others can be found throughout the wide field.Want the stars back? Just slide your cursor over the picture.M86 and friends

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