Like how we can see Venus and Mars sometimes. And if they are all stars, why can’t see planets that revolve around those stars?
In: Physics
Stars emit light. They are like giant candles. Most of what you see in the night sky stars that are very bright but very far away.
We can see “local” planets like Mars and Venus sometimes for the same reason we can see the moon. The sun (a star) reflects its light off of those planets and they are close enough for us to see with the naked eye.
Planets around other stars are too far away for us to see.
If you really want to learn about the stars and planets in your very own visible sky, download an app call star tracker (or something similar for your device).
You point it at the sky and it tells you exactly what you are looking at. It also gives you updates when new events are visible in your hemisphere.
I love it!!
Today some of the stars we see are actually satellites, but yes, you’ve always been able to see some of the planets of our solar system in the night sky. That’s why they’re called planets!
The ancient Greeks observed that most of the stars stayed in fixed positions in the sky. They named them and grouped them into constellations and used them to navigate. However they also noticed that some of the stars appeared to move from night to night. Not many, just a few. They referred to these moving stars as ‘wanderers’, or, in ancient Greek ‘planetes’.
These were the near planets in our solar system, and it’s why they’re named after Greek gods: Mercury, Venus, Mars, Jupiter, and Saturn.
Planets from our own solar system appear bright in the night sky because we’re seeing their “day” sides, i.e. the side that sunlight is hitting. If you were to launch up into space from Earth in the day time, you’d see that Earth is incredibly bright against the blackness of space too.
Stars are much, much, much farther away, but produce their own light, which eventually reaches us. A tiny fraction of the light that reaches us may have bounced off a planet, but the distance is too great for us to be able to see 2 distinct points of light, even with incredibly powerful telescopes. In fact, many stars that we see as single points are actually binary systems – 2 stars orbiting each other.
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