Introduction into Astronomy

What is Astronomy?

Astronomy is another branch of science. Astronomy is the study of celestial objects such as stars, moons, galaxies, and other particles in our universe. Scientists who study these things are called astronomers.

There are also different branches of astronomy.

The Branches of Astronomy

  1. Cosmology- the study of how the universe began
  2. Stellar Astronomy- the structure of stars and how they began
  3. Galactic Astronomy-the study of the Milky Way
  4. Solar astronomy- the study of the sun

There are many more branches of astronomy as these are only a few of the thousands of branches of astronomy.

Stars

Stars are large balls of gasses, mostly hydrogen and helium. Stars have different life stages.

A Star’s Life

  1. Stars first start out as a nebula. A nebula is a cloud of gases and dust, mostly hydrogen.
  2. Gravity pushed the clouds of the nebula together, forming a protostar. While this is happening, the hydrogen molecules turn into helium molecules.
  3. Gravity pushes the protostar even closer together to form a star.
  4. The star eventually cools and turns red. This stage is called a red giant. Helium atoms combine to become carbon atoms.
  5. The star becomes a white dwarf  when the helium is gone and carbon cannot be formed. This is the end of the star’s life.

What are Planets?

Planets are balls of gases and dust or rock that orbit a star. They also rotate on their axis.

Rotation, Revolution, and Orbit

Rotation is  the planet turning on it’s axis. Revolution is the planet moving around a star. Orbit is the path taken for a planet to go around a star

What is a Solar System?

A Solar System is a star with the planets and other object around it. Asteroids are rocks that orbit a star.

Our Solar System

Our solar system consists of eight planets orbiting the sun (the sun is a star).

  • Inner Planets/Rocky Planets
    • Mercury- Mercury is the closest planet to the sun.  One day on Mercury is 59 earth days. One year is 88 Earth days. Mercury has no moons.
    • Venus- Venus is the hottest planet in our solar system. It is hotter than Mercury because Venus has yellow clouds that do not let the heat escape the planet. Venus has no moons
    • Earth- Earth is the only known planet in the universe that has life. The Earth has 1 moon. The Earth’s moon formed when an asteroid hit the Earth as it was forming. The particles formed together and made the moon.
    • Mars- Mars is the fourth planet from the sun. Mars has 2 moons
  • Asteroid belt- the asteroid belt is a “ring” of asteroids between Mars and Jupiter.
  • Outer Planets/Gas Planets
    • Jupiter- Jupiter is the largest planet in our solar system. Instead of being hard and solid, Jupiter is made out of gases. Jupiter also has many storms. It’s biggest one is the Red Spot. Jupiter has faint rings. It has 63 known moons. Out of those, 17 are unconfirmed.
    • Saturn- Saturn has seven beautiful rings made of rock. Saturn has 62 moons. Out of those, 9 are unconfirmed.
    • Uranus- Uranus has very faint rings. Also, Uranus is tilted 98 degrees so that the poles are on the sides. It has 27 moons
    • Neptune- Neptune is the farthest and coldest planet from the sun. Neptune has 13 moons.

Moons

A moon is an object that orbits around a planet. A moon is like a natural satellite.

Dwarf Planets

Dwarf planets are objects that  orbit the sun but are too small to be a planet. There are six known dwarf planet. Pluto was a dwarf planet that was originally considered a planet. Since scientists discovered that Pluto’s orbit is diagonal around the sun and that Pluto is very small, they make it a dwarf planet.

Galaxies

A galaxy is a group of stars and dust. There are three types of galaxies

  • Spiral Galaxy- A spiral galaxy is shaped like a disk. It is arranged around a bright center point.
  • Irregular Galaxy- An irregular galaxy does not have a specific shape. Irregular Galaxies have a lot of gasses and dust in them, which makes it very bright.
  • Elliptical Galaxy- This is an oval-shaped galaxy. Elliptical Galaxies are classified as numbers and letters. E0 is the most circular while E7 is the most thin and oval shaped type of Elliptical Galaxy.

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