Fundamental Concepts in Networking and Astronomy

Unit 3: Network Computing and Protocols

Firewall: A software program that helps screen out hackers, viruses, and worms that try to reach your computer over the internet.

ADSL: A device used to connect a computer or router to a telephone line which provides the DSL service to connect to the internet broadband communications technology.

Router: This is a hardware device that routes data from a local area network (LAN) connection.

How Does Network Computing Work?

• IP Address: A numerical label assigned to each device.
• HTML: The language for creating web pages.
• URL Address: The protocol used for referencing online addresses.

Communication Protocols

• TCP: The suite of communications protocols used to connect hosts on the internet.
• FTP: An open protocol standard that is widely used to transport and receive large files.

Unit 4: Astronomy and the Universe

• Star: A large glowing ball of gas that generates heat and light through nuclear fusion.
• Planet: A moderately large object that orbits a star. It shines by its reflected light.
• Moon: An object which orbits a planet.
• Asteroid: A relatively rocky and small object which orbits a star.
• Comet: A relatively small and icy object which orbits a star.
• Star (Sun): All the material which orbits it, including its planets and moons.
• Nebula: An interstellar cloud of gas and dust.
• Galaxy: A great island of stars in space all held together by gravity and orbiting a common center.
• Universe: The sum of all matter and energy; that is, everything within and between all galaxies.

Where Do We Come From?

The first atoms were created in the Big Bang; more complex atoms were created in stars. We are star stuff.

How Large Is Our Galaxy?

• The Sun: 26,000 light-years from the center of the Milky Way Galaxy.
• The Milky Way: 80,000 to 120,000 light-years across and less than 7,000 light-years thick. We are located on one of its spiral arms, out towards the edge.

How Far Away Is the Nearest Galaxy?

Andromeda is the nearest galaxy. It’s about 2.5 million light-years from the Milky Way.

How Large Is the Universe?

Space is BIG. For example, what is the distance between the Earth and:

• The Moon: 384,000 kilometers
• The Sun: 1 AU (150,000,000 km)
• Alpha Centauri (nearest star): 4.2 light-years (266,000 AU)
• Center of the Milky Way Galaxy: 26,000 light-years (1.65x10⁹ AU)

If we only used kilometers or meters, the numbers would get out of hand very fast. The Earth rotates around its axis once every day!