Viewing The Universe
What is astronomy?..
Objectives
- Describe: characteristics of the universe in terms of time, distance, and organization.
- Identify: the visible light and nonvisible parts of the electromagnetic spectrum.
- Compare: refracting telescopes and reflecting telescopes.
- Explain: how telescopes for nonvisible electromagnetic radiation differ from light telescopes.
Vocabulary
Light year
The distance light travels in one year which equals approx. 10 trillion km per year or 6 trillion miles per year. The light-year is mostly used to measure distances to other stars. Distances measured in fractions of a light-year (or in light-months) usually involve objects within a star system. Distances measured in light-years include distances between nearby stars, such as those in the same spiral arm.
Astronomical unit
The average distance between the earth and the sun which Is approx. 150 million km. The distances are approximate mean distances. It has to be taken into consideration that the distances between celestial bodies change in time due to their orbits and other factors. For example, The Earth is 1.00 ± 0.02 AU from the Sun
Electromagnetic
Arrangement of electromagnetic radiation including radio waves, visible light from the sun, gamma rays, x rays, ultraviolet rays, infared waves and microwaves according to the wave lengths. It is the range of wavelengths or frequencies over which electromagnetic radiation extends.
Universe
All existence, and planets, stars, galaxy, the continents of intergalactic space and all matter and energy.
Refracting telescope
A telescope that uses a set of lenses to gather light from distant objects.
Reflecting telescope
A telescope that uses a curved mirror to gather and focus light from distant objects.