I’ve always thought that stars in the sky are well, stars. But I just started to wonder, that are they just other stars or can we also see planets and such with our naked eyes? Like can the star be so bright that it could reflect the light from the planet so we can see it with just our eyes? Or are they all just other stars like our sun?
In: Physics
You can see planets with the naked eye! Two of the brightest spots you see in the sky are actually venus (has a dense, very reflective atmosphere) and jupiter (just fucking huge). They reflect the light of the sun, just as the moon does.
But if you go out of our solar system, you just see stars with the naked eye. Exoplanets (planets, which are not in our solar system) are just too small to see them and they dont reflect enough light.
What we are refer to as “stars” in the night sky are either actual objects producing their own light or are objects reflecting the light from other sources. Most of the lights in the night sky are in fact stars though.
However, you are able to see a few objects that aren’t stars with the naked eye. The moon is probably the most obvious, but depending on the time of year and where you are, Jupiter, Saturn, Mars, and Venus are definitely visible with just your eyes. They generally look like very bright stars, with Mars having a reddish hue. Certain satellites and the ISS can also be seen unaided if you know where to look and are away from light pollution.
> Like can the star be so bright that it could reflect the light from the planet so we can see it with just our eyes.
Well, the only planets that can happen with are the ones in our solar system. This is because:
* They’re close by
* Their reflected light isn’t washed out by the sun, which is on the opposite side of the Earth
Even if a star were so bright that it illuminated a planet orbiting it brightly enough to be seen with the naked eye (which, to be clear, is absolutely impossible), the star itself would be so much brighter it would wash out the planet.
We *have* directly observed exoplanets by seeing them via the reflected light from their stars. However, this was with incredibly powerful telescopes and it’s not even how we normally observe exoplanets. Only a few dozen exoplanets have been directly observed.
I’ll put things you see into 2 groups: inside and outside our solar system.
####Inside the Solar System
You can obviously see the sun and moon. Some times you can see other planets, but they have to be positioned just right.
‘Shooting stars’ are actually comets, asteroids, and artificial satellites, not stars.
####Outside the Solar System
These would be known as celestial objects
The vast majority of the ‘stars’ you see are really stars. The light originates from a star. But light is effected by gravity, so it is not necessarily a straight line from you to the star.
A few ‘stars’ you see might actually be entire galaxies! I think as many as 9 are visible with the human eye depending on your location and time of year.
AFAIK we cannot see any other celestial objects like black holes (via accretion disk), nebulea, exoplanets, etc.
Here’s a fun fact that I feel like took me embarrassingly long to realize:
The sun traces a path through the sky every day from where it rises in the morning to where it sets in the evening. All of the planets (and the moon) will trace the same path through the sky as the sun. This is because all of the planets orbit the sun in the same plane.
Aren’t a lot of the points of light we see at night galaxies?
Others allready made pretty good answers. I want to give a small visualization on why you won’t see planets outside of our solar system.
Put two objects next to each other, when you are next to them the distance between them seems huge. Now the further you get away the smaller the distance will seem. Now even if the planet would emit the same amount of light as the sun, they would still seem as one object since we are several lightyears away from them.
Sooooo let’s convert into something feasable shall we?
Let’s say we were one lightyear away from our solar system and would watch the earth and the sun.
If you scale the sun down to a tennis ball (~6cm diameter) you’d need to place a pinhead ~7m apart from it. And if that wasn’t hard enough, you’d have to move ~400km away from those and still be able to tell them apart.
Latest Answers