Three decades after Cornell astronomer Carl Sagan suggested that Voyager 1 snap Earth’s picture from billions of miles away – resulting in the iconic Pale Blue Dot photograph – two astronomers now offer another unique cosmic perspective:
在美國康奈爾大學的天文學家，Carl Sagan提議，航海家1號從數十億英里外拍攝地球影像(從而產生傳統的淡藍色圓點照片)之後三十年。目前，兩位天文學家提供了，另一種獨特的宇宙視角：
Some exoplanets – planets from beyond our own solar system – have a direct line of sight to observe Earth’s biological qualities from far, far away.
一些系外行星(來自咱們太陽系以外的行星)具有一條直的視線，來從很遙遠處，觀察地球的生物特質。
Lisa Kaltenegger, associate professor of astronomy in the College of Arts and Sciences and director of Cornell’s Carl Sagan Institute; and Joshua Pepper, associate professor of physics at Lehigh University, have identified 1,004 main-sequence stars (similar to our sun) that might contain Earth-like planets in their own habitable zones – all within about 300 light-years of Earth – and which should be able to detect Earth’s chemical traces of life.
康奈爾大學藝術暨科學學院的天文學副教授，兼康奈爾大學卡爾薩根研究所所長，Lisa Kaltenegger與Joshua Pepper(美國里海大學物理學副教授)已經確認1004顆，在適宜居住區域中，可能具有類地球行星的主序(出現在恆星顏色對亮度之圖中，連續且獨特的恆星帶)恆星(類似咱們太陽)。它們全在離地球大約3百光年內，因此應該能發現地球生命的化學蹤跡。
The paper, “Which Stars Can See Earth as a Transiting Exoplanet?” was published Oct. 21 in the Monthly Notices of the Royal Astronomical Society.
該篇“哪些恆星能將地球視為一顆凌日系外行星？”的論文，發表於2020年10月21日的英國《皇家天文學會月報》期刊。
“Let’s reverse the viewpoint to that of other stars and ask from which vantage point other observers could find Earth as a transiting planet,” Kaltenegger said. A transiting planet is one that passes through the observer’s line of sight to another star, such as the sun, revealing clues as to the makeup of the planet’s atmosphere.
Kaltenegger宣稱：「讓咱們將觀測點反轉到其他恒星，並問其他觀測者，從哪個有利地點，能發現地球是一顆凌日行星。」凌日行星是穿過觀察者視線，通過另一顆恆星(諸如太陽)的星體。這能揭露有關地球大氣組成的諸多線索。
“If observers were out there searching, they would be able to see signs of a biosphere in the atmosphere of our Pale Blue Dot,” she said, “And we can even see some of the brightest of these stars in our night sky without binoculars or telescopes”.
她宣稱：「如果觀察員們在那裡搜尋，他們將能在咱們淡藍色圓點的大氣中，發現生物圈的諸多跡象。而且甚至能在沒有雙筒望遠鏡或望遠鏡的情況下，看見其中於咱們夜空中，一些最明亮的恆星。」
Transit observations are a crucial tool for Earth’s astronomers to characterize inhabited extrasolar planets, Kaltenegger said, which astronomers will start to use with the launch of NASA’s James Webb Space telescope next year.
對描繪有居住者之太陽系外行星特性的地球天文學家們而言，凌日觀測是一項至關重要的工具。隨著明年美國航太總署所屬詹姆斯韋伯太空望遠鏡的發射，天文學家們將開始利用該項工具。
But which stars systems could find us? Holding the key to this science is Earth’s ecliptic – the plane of Earth’s orbit around the Sun. The ecliptic is where the exoplanets with a view of Earth would be located, as they will be the places able to see Earth crossing its own sun – effectively providing observers a way to discover our planet’s vibrant biosphere.
不過，哪些恆星系能找到咱們？擁有此科學關鍵的是地球黃道(地球繞太陽的軌道平面)。黃道是系外行星具有地球能被發現的視域處，因為此些會是能看到地球越過其太陽的地方。這有效地為觀察者提供了一種，發現咱們行星充滿活力之生物圈的方式。
Pepper and Kaltenegger created the list of the thousand closest stars using NASA’s Transiting Exoplanet Survey Satellite (TESS) star catalog .
使用美國航太總署所屬凌日系外行星勘測衛星(TESS)的恆星目錄，Pepper及Kaltenegger創建了，千顆最靠近的恆星一覽表。
“Only a very small fraction of exoplanets will just happen to be randomly aligned with our line of sight so we can see them transit.” Pepper said. ”But all of the thousand stars we identified in our paper in the solar neighborhood could see our Earth transit the sun, calling their attention.”
Pepper宣稱：「只有極小一部分系外行星，會碰巧隨機與咱們的視線對齊，因此咱們能看到它們凌日。不過，在論文中，於太陽附近被確認的所有千顆恆星，可能看見地球凌日，這引起了他們的注意。」
“If we found a planet with a vibrant biosphere, we would get curious about whether or not someone is there looking at us too,” Kaltenegger said.
Kaltenegger宣稱：「倘若發現一顆充滿活力之生物圈的行星，她們會對，是否有人也在凝視著咱們感到好奇。」
“If we’re looking for intelligent life in the universe, that could find us and might want to get in touch” she said, “we've just created the star map of where we should look first.”
她宣稱：「倘若人們正在尋找宇宙中，能發現咱們且可能希望取得聯繫的有智慧生命，她們正好已經創建了，何處應該首先找尋的恆星圖。」
原文網址：https://news.cornell.edu/stories/2020/10/smile-wave-some-exoplanets-may-be-able-see-us-too
翻譯：許東榮
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