How the universe is organized

The visible universe…… basically everything. Millions of super galaxy clusters arranged in threads and sheets. The local Super galaxy cluster ……. the group of galaxy clusters that contains our Galaxy.  The local galaxy cluster…… the one that contains the Milky Way . That’s our Galaxy. Local means us.

The Milky Way Galaxy……. A group of billions of stars arranged in a flat disk sort of like a CD the stars are arranged with two “arms” that spiral out as the galaxy spins Our sun “sol” is in the outer edge of one of these spiral arms. These distances are so big we just can’t imagine them. To measure these distances we use light. It is the fastest thing we know. It travels at 300 000 km /second In 1 year it can go 9 460 000 000 000 km This is called a LIGHT YEAR or L.Y.

The Solar System…. The sun is at the center The Solar System….. The sun is at the center. It contains most of the mass. Orbiting around the sun are : i. Planets: Rocky or terrestrial Mercury Venus Earth Mars Gas giants (They all have rings) Jupiter Saturn Uranus Neptune These have enough gravity to have moons

ii. Dwarf planets: Pluto These are too small to have moons. Their gravity isn’t strong enough to deflect a comet. Brand New Discovery this year Planet IX There is a huge mass way past Pluto we haven’t seen it yet but it’s gravity is so big it’s deflecting the orbits of asteroids in the Kuiper Belt and making them more eliptical

Other heavenly bodies iii. Asteroids: Rocky pieces too small to be planets. Space rubble. Found in a belt between Mars and Jupiter. iv. Comets: Heads of ice and rocks and a long bright tail. They live in the Kuiper Belt on the edge of the solar system. They have very long elliptical orbits. Satelites: Small celestial bodies that orbit another celestial body that is not a star. Our moon is our only natural satelite. We have many man-made satelites (TV, Google Earth, Landsat, etc.)

Distances within our solar system Inside the solar system the distances are smaller so we use a new measurement. ATRONOMICAL UNITS or A.U. 1 AU is the distance from the sun to the earth 150 000 000 km There are approximately 63 067 AU in an LY Oh MY!

Habitable zone: The region around a star where life could be able to exist. Life as we know it needs water and light. Life could exist in a region around a star where the temperature allows the surface to have liquid water.   It depends on the size and brightness of the star as well as the distance of the planet or moon. In our solar system the habitable zone is between Venus and Mars. But we are also looking for life on the moons of Jupiter and Uranus. 

Habitable zone