Astronomy Picture of the Day

Explanation: Ferdinand Magellan and his crew had plenty of time to study the southern sky during their famous voyage around the world. As a result, two fuzzy cloud-like objects, not visible to northern hemisphere dwellers, are now known as the Clouds of Magellan. These star clouds are small irregular galaxies, satellites of our larger Milky Way spiral galaxy. The Large Magellanic Cloud (LMC) pictured above is only about 180,000 light-years distant - the only known galaxy closer is the Sagittarius Dwarf. Both the LMC and the Small Magellanic Cloud (SMC) are joined to the Milky Way by a stream of cold hydrogen gas. An unusual effect called gravitational lensing has recently been detected in a few LMC stars, and there is hope this could tell us important information about the true composition of our universe.

麥哲倫及其船員在著名的環球航行中，有非常多的時間觀察南半球的星空。 因此，現在南天二兩個瀰漫、北半球住居不得見的雲狀天體，就稱為是麥哲倫星雲。 這二團“星雲”是我們銀河系（大螺旋星系）的伴星系，其分類為不規則小星系。 上圖所呈現的大麥哲倫星系，距離我們大約18萬光年，唯一已知比它還近的星系，是人馬矮星系。 大麥哲倫星系和小麥哲倫星系，都有橋狀的冷氫氣流與銀河系相連。 最近在一些大麥哲倫星系的恆星中，發現了一種名為重力透鏡效應的不尋常現象，這種現象可能含有關於我們宇宙真正組成的重要信息。