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The Earth’s Atmosphere Can Cause Stars to Look Odd in the Night Sky

-- Heidi | July 3, 2021

Question:

Hi, hopefully you can learn me something new!

I’ve been curious for so many years of what phenomenon I actually witnessed in the night sky. This was in the morning in April in northern Norway, so it’s still pitch dark outside, and middle of nowhere (no light pollution). It was an amazing clear starry sky and I was randomly looking at these two stars that was “close” to eachother. One was brighter than the other and I was paying attention to the less brighter one. Both where still. Suddenly over a course of maybe 7-8 seconds or less it expanded to a point where it had tripled in size compared to the other one. Slowly right after it shrunk in size during maybe 10 seconds, to a point it had completely disappeared. It never re-emerged during my gazing.

I hope you can give my space brain some ease.
Thanks in advance!

-- Heidi

Answer:

What you describe sounds a lot like some of the effects that the Earth’s atmosphere can have on the light from stars as that light passes through different layers and constituents. For example, the “expansion” of the star you were watching could have been caused by clouds in the Earth’s atmosphere passing in front of the star, causing the light from the star to blur and broaden. Subsequently, when the star disappeared, this could also have been caused by clouds passing in front of the star, but this time clouds which were thick enough to completely block the light from the star.

-- Jeff Mangum

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