Question

universe

• began about 13.7 billion years ago with the
• the universe is
• origin, properties, processes and evolution :

organization of the universe

• nearest part of universe is our
• part of a galaxy: stars, dust, & gas bound by gravity.
• our galaxy :

measuring distances in the universe

• astronomical unit ( ) = average distance between earth & sun.
• 150 million km
• speed of light
• 300,000 km/sec, in one year 9.46x10¹² km = a (ly)
• after the sun the next nearest star is 4.22 ly away

visible electromagnetic radiation

• all the wavelengths of em radiation.
• humans can only see
• white light thru a = rainbow of colors.
• different wavelengths
• shortest blue and violet, red is longest.

invisible electromagnetic radiation

• (ir: below the red) longer than visible light
• radio waves are longer
• (uv: beyond the violet)
• x - rays and gamma rays are shorter.

telescopes

• galileo invented first in 1609.
• collects em radiation.
• telescope - collects visible light.
• 2 types refracting & reflecting.

refracting telescopes

• refraction - of light by lenses.
• objective lens bends light as it passes thru focuses the light to be magnified by

reflecting telescopes

• isaac newton invented.
• uses curved to focus & gather light.
• light is reflected by curved mirror to second mirror. reflects light to eyepiece.
• can be made very

telescopes for invisible emr

• for any type of emr.
• problem: earths shields against much emr.

09/22/2

Explanation:

The notes cover topics related to the universe such as its origin, organization, distance - measurement, electromagnetic radiation, and telescopes. Filling in the blanks requires knowledge of basic astronomy concepts.

Answer:

• The universe began about 13.7 billion years ago with the Big Bang.
• The origin, properties, processes and evolution are studied in astronomy.
• Nearest part of universe is our solar system.
• Part of a galaxy: stars, dust, & gas bound by gravity is a stellar system.
• Our galaxy is the Milky Way.
• Astronomical unit (AU) = average distance between Earth & sun.
• 300,000 km/sec, in one year 9.46x10¹² km = a light - year (LY).
• Humans can only see visible light.
• White light thru a prism = rainbow of colors.
• Infrared radiation (IR: below the red) longer than visible light.
• Ultraviolet radiation (UV: beyond the violet).
• Galileo invented first telescope in 1609.
• Optical telescope - collects visible light.
• Refraction - bending of light by lenses.
• Objective lens bends light as it passes thru focuses the light to be magnified by eyepiece.
• Isaac Newton invented. Uses curved mirror to focus & gather light.
• Can be made very large.
• Problem: Earth's atmosphere shields against much EMR.