NASA资助的研究表明，太阳在银河系中的运动轨迹以及其早期的剧烈活动可能对地球气候产生了深远影响1。研究发现，日光层——太阳产生的保护性磁场——可能在约200万至1400万年前间的多个时期出现收缩，导致地球直接暴露于星际环境1。具体而言，日光层收缩事件发生在约200-300万年前、600-700万年前和1300-1400万年前1。计算机模拟显示日光层可能收缩至小于地球轨道的范围1。深海沉积物、南极冰雪和月球样本中发现的星际尘埃元素与这些收缩时期相对应1，表明这些事件可能引发了冰河期。
早期太阳的另一项活动同样显著。研究指出，太阳的超耀斑事件可能产生了一氧化二氮这种强效温室气体，其效能约为二氧化碳的300倍1。仅需10%的实验室产生的一氧化二氮就可将赤道附近温度升至华氏41度（摄氏5度）1，足以维持年轻地球上液态水的存在1。约30亿年前太阳亮度仅为现在的70%1，这些超耀斑产生的温室气体在当时的低光照条件下尤为关键。研究已于2026年8月21日发表在《天文与天体物理学年评》和《天体物理学期刊快报》上1。
Two NASA-funded studies reveal that the Sun's motion through the galaxy and intense superflare events in the early solar system may have significantly influenced Earth's climate.1 Researchers found that the heliosphere—the Sun's protective bubble of charged particles—likely contracted at multiple points during Earth's history, potentially exposing the planet to harsh interstellar conditions.1 Computer simulations indicate the heliosphere may have shrunk to a size smaller than Earth's orbital radius.1 Three major contraction events occurred approximately 2–3 million years ago, 6–7 million years ago, and 13–14 million years ago.1 Evidence for these events appears in deep-sea sediments, Antarctic ice cores, and lunar samples, where researchers identified interstellar dust elements corresponding to these time periods.1
The heliosphere's contractions may have triggered ice ages on Earth, but the studies also reveal that the early Sun's powerful superflares likely had a warming effect. These superflares are thought to have produced nitrous oxide, a greenhouse gas approximately 300 times more potent than carbon dioxide, which may have kept the young Earth warm enough to maintain liquid water.1 Simulations suggest that just 10 percent of laboratory-produced nitrous oxide levels would be sufficient to raise equatorial temperatures to 41 degrees Fahrenheit (5 degrees Celsius).1 This warming mechanism was particularly critical given that approximately 3 billion years ago, the Sun's brightness was only 70 percent of its current output.1 Both studies were published on August 21, 2026, in the Annual Review of Astronomy and Astrophysics and The Astrophysical Journal Letters.1
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