GALAXIES

–          A galaxy is an extremely large area of space that contains billions and billions of stars along with gases and dust.

–          Our solar system belongs to the “Milky Way Galaxy.”  The Milky Way Galaxy is approximately 100 000 light years wide.  This means if a light was turned on at one end of the galaxy, it would take 100 000 years for that light to reach the other side of the galaxy.

–          The Milky Way Galaxy is a spiral-shaped galaxy and our solar system is on one of the outer spirals of the galaxy.

–          Every one of the 400 billion stars in the Milky Way Galaxy are constantly moving.  As our Sun moves within the Milky Way Galaxy, all the planets stay in orbit around it.

TYPES OF GALAXIES

–          Scientists have named three types of galaxies based on their shapes:

  • Spiral Galaxies, such as the Milky Way Galaxy, are shaped as spirals flowing around a central bulge of stars.
  • Elliptical Galaxies are shaped as ovals.
  • Irregular Galaxies do not have a regular shape and all appear different from one another.

UNUSUAL GALAXIES

–          Due to our ability to collect light from very distant places (by using the HST), scientists are constantly discovering new things about galaxies.

–          Remember that everything in the universe is constantly moving.  Due to this, galaxies can actually collide and rearrange their star composition.  Some smaller galaxies can actually be “eaten” or incorporated into large galaxies.

STAR CLUSTERS

–          A cluster is when objects are packed very closely together.  Therefore, a star cluster is multiple (10 to a million) stars grouped very closely together.

–          Star clusters can be found within galaxies.

–          Our Sun is not in a star cluster.  In fact, the next closest stars to our Sun are Proxima Centauri and this dwarf star is over 4.24 light years away.

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