Structure of the Universe

elliptical orbits

an oval-shaped path of a celestial body. The Earth, as well as all the other planets in the Solar System, follow this type of orbit around the Sun. The shape is created by the varying pull of forces, such as gravity, on two objects, such as the Sun and a planet

Planet

as an object (celestial body) that: · orbits the sun · has sufficient mass to be round, or nearly round · is not a satellite (moon) of another object

universe

Space and all the matter and energy in it-all space-time, matter, and energy, including the solar system, all stars and galaxies, and the contents of intergalactic space, regarded as a whole

Star

A ball of hot gas, primarily hydrogen and helium, that undergoes nuclear fusion. (Example: our Sun)

galaxy

A huge group of single stars, star systems-planets, dust, and gas bound together by gravity-

Moon

A natural satellite that revolves around a planet.

Virgo Supercluster

contains the Local Group with our galaxy, the Milky Way. It's sometimes called the Local Supercluster. It is thought to contain over 47,000 galaxies.

spiral galaxy

galaxies have a bulge at the center and spiral arms made of gas, dust, and stars (the Milky Way is an example of this type of galaxy)

Milky Way Galaxy

galaxy in which we live is shaped like a flat pinwheel, this type of galaxy is a barred spiral galaxy. Our solar system is located in the Orion Arm of this barred spiral galaxy.

Gravity

is a force of attraction that exists between any two masses, any two bodies, any two particles. is not just the attraction between objects and the Earth. It is an attraction that exists between all objects, everywhere in the universe.

solar system

the collection of eight planets and their moons in orbit around the sun, together with smaller bodies in the form of asteroids, meteoroids, and comets.

Inertia

The tendency of an object to resist a change in motion

Local Galaxy (Galactic) Group

is the galaxy that includes the Milky Way-this comprises more than 54 galaxies, most of them dwarf galaxies—its gravitational center is located somewhere between the Milky Way and the Andromeda Galaxy

Orion Arm of the Milky Way Galaxy

or Orion-Cygnus Arm is a minor spiral arm of the Milky Way galaxy. It is of interest because our Solar System (including the Earth) is inside it.