How many moons are there in the Solar System? Week #AstroMiniBR

every saturday, the TechWorld and #AstroMiniBR bring together five relevant and fun astronomical curiosities produced by the contributors to the Twitter profile to disseminate knowledge of this science, which is the oldest of all!

This week, we’ll learn more about the movement of planets, the moons of the solar system, the colors in astronomical images, and exoplanets. Come on?

#1:  Uranus, are you okay?

Ever wonder how planets rotate? Now you can know! In the animation we can see how the other planets in the solar system carry out the rotation process, the same process the Earth goes through and defines day and night. Basically, when rotating around an axis, the planets have one face facing the Sun. This phase will be day and the other will be at night. It’s not a coincidence, but most planets have more or less aligned axes of rotation. This happens by conserving the angular momentum of the protoplanetary cloud. Our entire solar system was born from a spinning cloud. Upon collapsing, this cloud formed a star, our Sun, and a disk. And from the disc, the planets were born. So everyone must have an aligned rotation axis. However, with interactions and collisions with other bodies, these axes are slightly displaced. In extreme cases, like Uranus, collisions can significantly alter the planet’s rotation!

#2: How many moons are there in the Solar System?

There are other moons in the solar system besides our Moon! In fact, it is quite common for planets to have satellites, just like Earth. It’s actually so common that some planets have multiple moons! The inner planets, Mercury and Venus, have no natural satellites. Our neighbor, Mars, has two moons: Phobos and Deimos. The outer planets, on the other hand, being larger, have a much larger number of moons. Jupiter, the largest planet in the Solar System, has 79 moons. Saturn, which is in the lead in this regard, has 82 moons. Uranus has 27 and lastly, Neptune has 14 moons. A curiosity that few people know: natural satellites of other planets are also called “moons”, but with a lowercase “l”. Our natural satellite is called the Moon, with a capital “l”!

#3: Is this photo real?

Astronomy lovers of all ages sometimes ask themselves “does this photo have artificial or real color?”. Using artificial colors in astronomy is a common feature. First, because many of the images are at wavelengths that the human eye can’t see, so we need artificial colors to see the data, naturally. Also, artificial colors help to bring out contrasts. However, it is noteworthy that even if the images are artificially colored, the data is real and what we are seeing is real! But in case you’ve wondered, we can see above what Saturn looks like in natural colors! The planet’s atmosphere is made up of ammonia ice and methane gas, which have these pastel colors. Also, the dark spot is one of the planet’s moons, Enceladus. You can find more information here.

#4: What movement of planets within the Solar System

How is the movement of other planets in the Solar System? Like Earth, other planets have various motions, the two main ones being rotation and translation. Rotation is the name of the movement when the planet rotates like a pawn around itself. Translation is the name of the movement when the planet rotates around the Sun. Rotation defines day and night, just like on Earth. While translation defines the duration of one year. In astronomy we use the length of Earth’s days and years as a comparative reference. Some things are impressive, with the fact that the day length on Jupiter is only 10 hours. In other words, the largest planet in the Solar System rotates faster than Earth. Another interesting fact is that Neptune takes 165 Earth years to complete a revolution around the Sun! This is because the planet is farther away from the Sun, so it’s natural.

#5: Have you ever seen a planet outside the Solar System?

Have you ever heard of exoplanets?! The exo prefix refers to the fact that they are planets outside the Solar System. Today we know about 4,000 planets orbiting other stars! Some look like the Sun, others less so. There are different techniques for detecting these planets. Some involve studying the host star’s light, others motion. However, observing exoplanets directly is more complicated. Have you ever tried to observe the starry sky near a big city? The street light dims the starlight. The same happens when we try to observe other planets in other planetary systems. Starlight dims the light of planets. So, in order to be able to observe the planet we need to block the starlight, and that’s what’s happening in the gif. By blocking the star’s light we can observe the planet (small moving point). Over the years we have been able to map out what its orbit looks like!

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