Our Solar System

What are Galaxies? A collection of nebulae, stars and dust that form a solar system. The stars found in Elliptical Galaxies are often very old. This is because elliptical galaxies don't actively create new stars.  The only stars found with in them were created along time ago. Although they are usually smaller, this type of galaxy can be large. Most have only a few thousand stars, but some can have billions of stars. The stars in an elliptical galaxy are often very close together making the center look like one giant star.  If the Earth were inside an elliptical galaxy it would be bright both day and night. Irregular Galaxies are simply all the galaxies which are not spiral or elliptical. They can look like anything and have many different characteristics. Many irregular galaxies probably used to be spiral, or elliptical until they had some kind of accident which changed them such as crashing with another galaxy. Many other irregular galaxies probably were never spiral or elliptical; they simply didn't evolve that way. We live in a spiral galaxy – The Milky Way. Irregular Spiral Elliptical

What are Nebulae? Nebula are cosmic clouds of gas and dust floating in space. Nebulae are the basic building blocks of the universe. They contain the elements from which stars and solar systems are built. The Bad Astronomer Nebulae The Bad Astronomer – not a very good video but gives a simple explanation of nebulae. Nebulae – 6 min video of all the different nebula.

What are stars made from? A star is a huge ball of gas, with a central core that is very hot and produces lots of energy. A star is held together by gravity. What are stars made from?

How did the Solar System form? What is the Solar System? The Solar System is made up of all the planets, moons, comets and asteroids that orbit our Sun. How did the Solar System form? Everything in the Solar System orbits or revolves around the Sun. The Sun contains around 98% of all the material in the Solar System. The larger an object is, the more gravity it has. Because the Sun is so large, its powerful gravity attracts all the other objects in the Solar System towards it. At the same time, these objects, which are moving very rapidly, try to fly away from the Sun, outward into the emptiness of outer space. The result of the planets trying to fly away, at the same time that the Sun is trying to pull them inward is that they become trapped half-way in between. Balanced between flying towards the Sun, and escaping into space, they spend eternity orbiting around the Sun.

What are Asteroids? Asteroids are small celestial bodies composed of rock and metal that move around the sun (mainly between the orbits of Mars and Jupiter). They are shaped like a star. Click on diagram for 3D version of asteroids.

Click on pictures for video links. What are Comets? A comet is made of dirty ice, dust and gas. When a comet gets close to the Sun, part of the ice starts to melt. The melted ice moves away from the comet forming its tail. Click on pictures for video links. Every time a comet comes close to the Sun, a part of it melts. Over time, it will completely disappear. A comet does not give off any light of its own. What seems to be light from the comet is actually a reflection of our Sun's light. Sunlight bounces off the comet's ice particles in the same way light is reflected by a mirror. A few comets come close enough to the Earth for us to see them with our eyes. Halley's Comet, for example, can be seen from Earth every 76 years.

What are Moons? A solid object that orbits a body other than the Sun. Phases of the Moon Click on picture for video link

Is Pluto really a planet? What are Planets? Planets are any of the large bodies that revolve around the sun in the solar system. Is Pluto really a planet?

The movement of all the components Click on diagram Describe the movement (speed) of the planets, moons, etc around the sun.