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Bright Object in the Sky with Varying Intensity

-- André | February 17, 2020

Question:

HI! Im from Portugal and long time ago, at night time, near summer, in the north of the sky, I notice an unusual star who tinted like an ordinary star, but a good bit brighter than Sirius start and with a fickle intensity. After around 30s his intensity drops until almost vanish and after around 30s his intensity come hight like before. It happen during 10min until, in one of his intensity drop, it vanish completely and didnt saw it after that. The star never moved and was for sure a start twinkling. What kind of phenomenon could have been?

-- André

Answer:

I suspect what you were seeing is a bright planet, such as Saturn, Venus, or Jupiter, whose brightness was being affected by the Earth’s atmosphere. These variations in the Earth’s atmosphere are seen most often as “twinkling” of stars, for example. If the object you saw was low in the sky, the amount of atmosphere that the object’s light has to pass through can be quite large, which can make the brightness variations quite large. The “unexplained celestial phenomena” section of this blog lists a number of posts on this effect.

-- Jeff Mangum

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