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.
2002 June 20
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.
2002 June 20
Explanation: Big and beautifulspiral galaxy M81,in the northern constellationUrsa Major,is one of thebrightestgalaxies visible in theskies ofplanet Earth.Thissuperblydetailed viewreveals its bright nucleus, grandspiral arms and sweeping cosmic dust lanes with a scalecomparable tothe Milky Way.Hinting at a disorderly past,a remarkable dust lane runs straight through thedisk, below and right of the galactic center,contrary toM81's otherprominentspiral features.The errantdust lane may be the lingering result ofaclose encounter betweenM81 and its smaller companion galaxy,M82.Scrutiny of variable stars in M81 (aka NGC 3031)has yielded one of the bestdetermineddistances for an external galaxy -- 11.8 million light-years.
Authors & editors:Robert Nemiroff(MTU) &Jerry Bonnell (USRA)
NASA Technical Rep.:Jay Norris.Specific rights apply.
A service of:LHEA atNASA/GSFC
&Michigan Tech. U.