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[视图资料] Astronomy Picture of the Day 2010-每日天文一图第四季

发表于 2010-07-19 09:46 | 显示全部楼层
2010 July 18

The Antennae Galaxies in Collision
Credit: NASA, ESA & B. Whitmore (STScI) et al.; Image processing: Davide De Martin

Explanation: Two galaxies are squaring off in Corvus and here are the latest pictures. But when two galaxies collide, the stars that compose them usually do not. That's because galaxies are mostly empty space and, however bright, stars only take up only a small amount of that space. During the slow, hundred million year collision, one galaxy can still rip the other apart gravitationally, and dust and gas common to both galaxies does collide. In this clash of the titans, dark dust pillars mark massive molecular clouds are being compressed during the galactic encounter, causing the rapid birth of millions of stars, some of which are gravitationally bound together in massive star clusters.

影像提供: NASA,ESA &B. Whitmore(STScI) et al.;Image processing: Davide De Martin
說明: 烏鴉座 (Corvus)內的二個星系正在發生碰撞,上面是它們的近況影像。當二個星系互撞時,它們內部的恆星通常並不會撞在一起,因為不管恆星看起來多麼明亮,它們只占據很小的空間,星系內大部份的空間多空無一物。但是在這種歷時數億年的緩慢碰撞中,大星系會透過重力作用把小星系,導致二個星系內無所不在的塵埃雲氣發生碰撞。在上面這種龐大天體互撞中,大質量分子雲所聚成的黝黑塵埃柱,會在星系近距離接觸時受到壓縮,使得數以百萬計的恆星在短時間內快速誕生,其中部份恆星會在重力的束縛下,形成大質量的星團
发表于 2010-07-22 00:59 | 显示全部楼层
2010 July 19

Dark River, Wide Field
Credit & Copyright: Rogelio Bernal Andreo

Explanation: A Dark River of dust seems to run from our Galactic Center, then pool into a starfield containing photogenic sky wonders. Scrolling right will reveal many of these objects including (can you find?) the bright orange star Antares, a blue(-eyed) horsehead nebula, the white globular star cluster M4, the bright blue star system Rho Ophiuchi, the dark brown Pipe nebula, the red Lagoon nebula, the red and blue Trifid nebula, the red Cat's Paw Nebula, and the multicolored but still important center of our Galaxy. This wide view captures in exquisite detail about 50 degrees of the nighttime sky, 100 times the size of the full Moon, covering constellations from the Archer (Sagittarius) through the Snake Holder (Ophiuchus), to the Scorpion (Scorpius). The Dark River itself can be identified as the brown dust lane connected to Antares, and spans about 100 light years. Since the Dark River dust lane lies only about 500 light years away, it only appears as a bridge to the much more distant Galactic Center, that actually lies about 25,000 light years farther away.

影像提供與版權: Rogelio Bernal Andreo

說明: 這條由塵埃組成的暗河,看似從銀河中心延伸匯流到星海之中,伴隨許多上相的星體。向右捲動影像,你可以找到以下星體嗎?紅巨星心宿二藍色馬頭星雲、白色球狀星團(M4)、藍色亮星心宿增四星(Rho Ophiuchi)、深棕色的煙斗星雲(Pipe nebula),紅色潟湖星雲(Lagoon nebula)、紅藍組成的三裂星雲(Trifid nebula)、紅色貓掌星雲,以及五彩繽紛的銀河系中心。這張廣視野 影像射手座(Sagittarius)穿過蛇夫座(Ophiuchus),然後到天蠍座(Scorpius),足足橫掛了50度,是滿月直徑的100倍。從心宿二所蔓延出來的棕色暗河,大概是100光年左右,距離我們約500光年,然而看起來卻像是一座橋,連接到25000光年之遙的銀河系中心
发表于 2010-07-22 00:59 | 显示全部楼层
2010 July 20

Lightning Over Athens
Credit & Copyright: Chris Kotsiopoulos

Explanation: Have you ever watched a lightning storm in awe? Join the crowd. Oddly, nobody knows exactly how lightning is produced. What is known is that charges slowly separate in some clouds causing rapid electrical discharges (lightning), but how electrical charges get separated in clouds remains a topic of much research. Lightning usually takes a jagged course, rapidly heating a thin column of air to about three times the surface temperature of the Sun. The resulting shock wave starts supersonically and decays into the loud sound known as thunder. Lightning bolts are common in clouds during rainstorms, and on average 6,000 lightning bolts occur between clouds and the Earth every minute. Pictured above, an active lightning storm was recorded over Athens, Greece earlier this month.

影像提供與版權: Chris Kotsiopoulos

說明: 你曾看閃電看到目瞪口呆嗎?世界上很多人都有過這樣的經歷。奇怪的是,沒人確切地知道閃電的成因,目前我們只知道在某些雲內,電荷產生分離,最後發生了劇烈的放電現象-閃電。但是在雨雲中,電荷為什麼會分離,到現在仍舊是炙手可熱的研究議題。閃電路徑十分曲折,如鉅齒狀,發生過程中對窄細的空氣柱快速地加熱到三倍的太陽表面溫度。而伴隨產生的激震波超音波銳減到巨大聲響,就是我們所聽到的雷聲。閃電總是伴隨在雷雨雲之中,平均每分鐘大概有6,000道閃電,從雷雨雲打到地球表面。這張精彩的影像是本月初在希臘地區,一個活躍的雷暴系統壟罩在雅典上空而拍下的。
发表于 2010-07-22 01:01 | 显示全部楼层
2010 July 21

The Crown of the Sun
Credit & Copyright: Alain Maury, Jean-Luc Dauvergne

Explanation: During a total solar eclipse, the Sun's extensive outer atmosphere, or corona, is an inspirational sight. Subtle shades and shimmering features that engage the eye span a brightness range of over 10,000 to 1, making them notoriously difficult to capture in a single photograph. But this composite of 7 consecutive digital images over a range of exposure times comes close to revealing the crown of the Sun in all its glory. The telescopic views were recorded from the Isla de Pascua (Easter Island) during July 11's total solar eclipse and also show solar prominences extending just beyond the edge of the eclipsed sun. Remarkably, features on the dim, near side of the New Moon can also be made out, illuminated by sunlight reflected from a Full Earth.

影像提供與版權: Alain Maury,Jean-Luc Dauvergne

說明: 在日全食期間,名為日冕的太陽外層大氣是個扣人心弦的景觀。令人神迷的日冕之微妙層次和搖曳結構,亮度的反差超過一萬比一,因此非常難用單張照片來呈現。不過,上面這幅由7張連續曝光影像所組合之照片,幾乎能捕捉日冕的完整風貌。這些望遠鏡影像是7月11日日全食時,在復活島拍攝的,在邊緣還可以看到太陽的日珥噴發。有趣的是,月亮背對太陽的那一面,也受到了地球的反射光所照亮,而呈現在這張照片中。
发表于 2011-08-21 22:32 | 显示全部楼层
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