GAL - Galaxies - OVERVIEW

Galaxies

Galaxy

Introduction

One day, we may have the ability to travel to other galaxies like you would see in popular movies such as "Star Trek". In the meantime, you will learn about the different types of galaxies scientists have discovered, their characteristics, and how they formed as you continue through your astronaut training program.

Essential Questions

  • What are the characteristics of the different types of galaxies?
  • What are superclusters?
  • What is dark matter?

Key Terms

Blue Shift - the phenomenon of a decrease in the electromagnetic wavelength of the radiation emitted by an object

Bulge  - the central sphere of dense stars found in the center of spiral galaxies

Dark Matter  - matter that does not produce or reflect radiation and takes up to 10 times the mass of visible matter

Disk  - the flattened portion of a spiral galaxy that contains the spiral arms

Galaxy - system of stars, gas, and dust held together by gravitational attraction

Halo  - a spherical area that encloses a galaxy and contains older pop ii and globular clusters

MACHO  - Massive Compact Halo Objects, such as dead stars, old neutron stars, or black holes

Parsec  - a distance from the Sun that would result in a parallax of 1 second of arc as seen from the Earth, a distance of 3.26 light years

Quasar  - massive and extremely remote celestial objects, which emit exceptionally large amounts of energy

Red Shift - the phenomenon of an increase in the electromagnetic wavelength of the radiation emitted by an object

Spiral Galaxy  - the most common type of galaxy; it is a flattened disk with spiral arms

WIMP  - Weakly Interactive Massive Particles

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