Earth
from Mars 從火星看地球 (24/5/2003)
太空，是一個很廣闊的地方，大得你想像不到，每一樣物件在宇宙中都細小得不能形容。地球在宇宙中，只是一個很小很小的藍點，基本上出了太陽系就會連地球都看不見了，可想而知，我們有多細小。在大氣層上看回地球的相就見得多了，由火星（由火星全球勘測者號太空船拍的）望回地球的相倒是第一次，你辦認到這是地球的甚麼地方嗎？想知答案的話，請看英文的解說。右上角的是什麼？當然是月球，不要告訴我你不知道呀，原來月球相對於地球來說，一點也不算細小。真是越看就越喜歡這張相，將來若果人類移到火星的話，望上太空，回看自己的老家時，就是這個樣子了。
Caption::
This is the first image of Earth ever taken from another planet that actually
shows our home as a planetary disk. Because Earth and the Moon are closer
to the Sun than Mars, they exhibit phases, just as the Moon, Venus, and
Mercury do when viewed from Earth. As seen from Mars by MGS on 8 May 2003
at 13:00 GMT (6:00 AM PDT), Earth and the Moon appeared in the evening
sky. The MOC Earth/Moon image has been specially processed to allow both
Earth (with an apparent magnitude of -2.5) and the much darker Moon (with
an apparent magnitude of +0.9) to be visible together. The bright area
at the top of the image of Earth is cloud cover over central and eastern
North America. Below that, a darker area includes Central America and
the Gulf of Mexico. The bright feature near the center-right of the crescent
Earth consists of clouds over northern South America. The image also shows
the Earth-facing hemisphere of the Moon, since the Moon was on the far
side of Earth as viewed from Mars. The slightly lighter tone of the lower
portion of the image of the Moon results from the large and conspicuous
ray system associated with the crater Tycho.
Credit::
NASA/JPL/Malin Space Science Systems
|
"Happy
Face" Crater on Mars 火星「笑臉」環形山 (23/5/2003)
火星上的一個奇怪環形山--笑臉環形山。正常的環形山都是圓形的，中央或許會突起，像它周圍那幾個便是正常的，但這個環形山樣子真可愛，是一個笑臉，有眼有口，就像是自己畫上去的。這環形山，正名為Galle環形山，以紀念德國天文學家Johann
Galle，直徑230公里，位於火星的南半球。環形山是隕石撞擊時形成的，地球也有很多環形山，月球表面則更多。
Caption::
The picture show Galle Crater, informally known as "Happy Face,"
as it appeared in early southern winter. The white-ish gray surfaces are
coated with wintertime carbon dioxide frost. The pattern of frost distribution
gives the appearance that "Happy Face" has opened its mouth.
Galle Crater is located on the east rim of Argyre at 51°S, 31°W. Sunlight
illuminates the scene from the upper left. Galle Crater is 230 km (143
mi) across.
Credit::
NASA/JPL/Malin
Space Science Systems
|
Eagle
Nebula 鷹狀星雲 (22/5/2003)
不經不覺已經經過了8年，記得8年前第一次見這張相時目定口呆，確實，很靚。除了色彩繽紛外，星雲本身的形態也很特別。之所以叫作鷹狀星雲，當然是因為它似一隻鷹，不似嗎？其實又真是不易看到，因為你現在只看到星雲的一部份，又是等有機會找另一張鷹狀星雲的相上來（已許下了不少空頭支票了，汗）。這星雲又名M16（是一個星表裏的編號），也是一處恆星誕生地，星雲中的氣體與塵埃一直孕育著初生恆星。記得不只一個人問過，幹嗎圖的右上角會了不見了，這是因為哈勃太空望遠鏡同時用4個相機拍攝，分別負責左上、右上、左下和右下4個位置，但第4個相機的視場比其餘3個細小而致，很多早期的哈勃照片都是這樣的。
Caption::
Eerie, dramatic pictures from the Hubble telescope show newborn stars
emerging from "eggs" — not the barnyard variety — but rather,
dense, compact pockets of interstellar gas called evaporating gaseous
globules (EGGs). Hubble found the "EGGs," appropriately enough,
in the Eagle nebula, a nearby star-forming region 7,000 light-years from
Earth in the constellation Serpens. These striking pictures resolve the
EGGs at the tip of finger-like features protruding from monstrous columns
of cold gas and dust in the Eagle Nebula (also called M16). The columns
— dubbed "elephant trunks" — protrude from the wall of a vast
cloud of molecular hydrogen, like stalagmites rising above the floor of
a cavern. Inside the gaseous towers, which are light-years long, the interstellar
gas is dense enough to collapse under its own weight, forming young stars
that continue to grow as they accumulate more and more mass from their
surroundings.
Credit::
Jeff
Hester and Paul Scowen (Arizona State University), and NASA
|
Tadpole
Galaxy 蝌蚪星系 (21/5/2003)
星系間的碰撞原來是很多的，甚至是由於星系之間的碰撞而令星系演化。這個蝌蚪星系距離我們420,000,000光年（很遠吧，想像到嗎？），又是一個星系碰撞的活生生例子，你見到那伸出來長長的尾，就是撞擊（其實未必一定是正面撞上，擦過也說不定）時被對方強大的重力吸引拉扯出來的，這條尾足足有280,000光年。除了蝌蚪星系外，你還可以見到很多一點點，其實每點你見到的都是一個星系，只是因為它們比蝌蚪更遠，看起來更細而已，這圖大約有6000個這樣的背景星系。
Caption::
In this stunning vista recorded with the Hubble Space Telescope's new
advanced camera, distant galaxies form a dramatic backdrop for disrupted
spiral galaxy Arp 188, the Tadpole Galaxy. The cosmic Tadpole is a mere
420 million light-years distant toward the northern constellation Draco.
Its eye-catching tail is about 280 thousand light-years long and features
massive, bright blue star clusters. One story goes that a more compact
intruder galaxy crossed in front of Arp 188 - from left to right in this
view - and was slung around behind the Tadpole by their gravitational
attraction. During the close encounter, tidal forces drew out the spiral
galaxy's stars, gas, and dust forming the spectacular tail. The intruder
galaxy itself, estimated to lie about 300 thousand light-years behind
the Tadpole, can be seen through foreground spiral arms at the upper left.
Following its terrestrial namesake, the Tadpole Galaxy will likely lose
its tail as it grows older, the tail's star clusters forming smaller satellites
of the large spiral galaxy.
Credit::
NASA,
H. Ford (JHU), G. Illingworth (USCS/LO), M.Clampin (STScI), G. Hartig
(STScI), the ACS Science Team, and ESA
|
Star
Formation Region IC4678 恆星誕生地 IC4678 (20/5/2003)
記得這張相曾經做過Science期刊的封面，而該期正以恆星誕生為專題。其實恆星跟人一樣，有生老死的階段，今次就讓我來介紹一些誕生的階段。恆星的母體就是星際雲，一些含有大量氣體和塵埃的地方，當那些塵越聚越多時，就會變為星了（很神奇吧？是的，宇宙中很多東西都都很神奇，其實中間還有很仔細的過程，留待日後再介紹吧）。IC4678位於人馬座方向，星際雲密度高，是一個恆星誕生地，相信於數百萬年後，就會有很多恆星誕生。（數百萬年對於恆星來說，是很短暫的）
Caption::
This extremely rich region of our galaxy, IC 4678 area in the Sagittarius,
illustrates brillantly the complex evolution cycle of matter in galaxies.
Molecular clouds, seen here as the obscuring nebulae, eventually condense
and turn into star formation regions. After millions of years, the new
born stars will have blown their initial envelope back into the interstellar
medium. Eventually, the cluster itself will dissolve, each star taking
its own path into the galaxy's giant whirl, mixing with the previous generations
of stars.
Credit::
Jean-Charles
Cuillandre (CFHT) and CFHT
|
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