Explanation: Celebrate the New Year with the Fireworks Galaxy!Also known as NGC 6946, the big, beautifulspiral galaxyis located just 10 million light-years away, behind a veil offoreground dust and stars in the high and far-offconstellation of Cepheus.From our vantage point in theMilky Way Galaxy, we seeNGC 6946face-on.In thiscolorfulcosmic portrait,the galaxy's colors changefrom the yellowish light of old stars in the core to young blue starclusters and reddish star forming regions along the loose, fragmentedspiral arms.NGC 6946 is bright in infrared lightand rich in gas and dust,exhibiting a furious rate of star formation.Nearly 40,000 light-years across, the nearby spiral isfittingly referred to as theFireworks Galaxy.Over the last 100 years, at least nine supernovae, thedeath explosionsof massive stars, werediscovered in NGC 6946.By comparison, the average rate for supernovae in the Milky Wayis about 1 per century.
Explanation: Here is what the Earth looks like during asolar eclipse.Theshadowof theMoon can be seen darkening part ofEarth.This shadow movedacross theEarth at nearly 2000 kilometers per hour.Only observers near the center of thedark circle see a total solar eclipse -others see a partial eclipse where only part of theSun appears blocked by the Moon.This spectacular picture of the 1999 August 11solar eclipsewas one of the last evertaken from the Mir spacestation.The two bright spots that appear on the upper left are thought to beJupiter and Saturn.Mir was deorbited in acontrolled re-entry in 2001.（注意圖上的兩個小點，是水星和金星）
Explanation: A mere seven hundred light years from Earth, in the constellationAquarius,a sun-like star is dying.Its last few thousand years have produced theHelixNebula(NGC 7293), a well studied and nearby example of aPlanetaryNebula,typical of this final phase of stellar evolution. A total of 10 hours of exposuretime have gone in to creating thisremarkably deepview of the nebula.It shows details of the Helix's brighterinner region, about 3light-years across, but also follows fainterouter halofeatures that give the nebula a span of well over six light-years.The white dot at the Helix's center is this Planetary Nebula's hot,central star.A simple looking nebula at first glance, the Helixis now understood to have a surprisinglycomplex geometry.（這張是NGC 7293: The Helix Nebula 星團）
Explanation: Globular star cluster 47 Tucanae is a jewel of the southern sky.Also knownas NGC 104, it roamsthe halo of our Milky Way Galaxyalong with some 200 other globular star clusters.The second brightest globular cluster (afterOmega Centauri)as seen from planet Earth, it lies about 13,000 light-years away andcan be spotted naked-eye near theSmall Magellanic Cloudin the constellation ofthe Toucan.The dense cluster is made up of several millionstars in avolumeonly about 120 light-years across.Red giant starson the outskirts of the cluster are easy to pick out as yellowish stars inthis sharptelescopic portrait.Globular cluster 47 Tuc is also home to exoticx-ray binary star systems.（這張照片很好的說明了在宏觀尺度上宇宙的無限性,照片裡的亮點絕大部分都是星團，注意不是恆星……）
Explanation: Celebrating 7 yearson the surface ofthe Red Planet,Mars exploration rover Opportunity now stands near therim of 90 meter wideSantaMaria crater.Remarkably, Opportunity and its fellowrover Spirit were initiallyintended for a 3 monthlong primary mission.Still exploring, the golf cart-sized robot and shadow (far right)appear in the foreground of this panoramic view of itscurrent location.The mosaic was constructed using images from the rover's navigationcamera.On its7 year anniversary,Opportunity can boast traversing a total of 26.7 kilometersalongthe martian surface.After investigating Santa Maria crater, controllers plan to haveOpportunity resume a long-term trek toward Endurance crater,a large, 22 kilometer diameter crater about 6 kilometers fromSanta Maria.During coming days, communication with the rover will be moredifficult as Mars moves close to alignment with the Sun as seenfrom planet Earth'sperspective.(古老荒涼又神秘的火星……)
