What are the two coordinates measured by an astrolabe?
- Azimuth
- Altitude
What are the steps when using an astrolabe?
- Face north
- Turn clockwise until you are in line with the object
- Record azimuth (degrees from north)
- Look up and measure altitude
What was the difference between the Geocentric and Heliocentric models and who proposed each?
The Geocentric model showed that the earth was in the centre of the universe and the Heliocentric model showed that the sun was in the centre of the universe. The Geocentric model was proposed by Aristotle and the Heliocentric model was proposed by Galileo.
Why don’t planets orbit in a circular motion?
Planets don’t orbit in a circular motion because the planet will want to move straight up but then gravity will pull it toward the sun causing an elliptical orbit.
What two pieces will a telescope always consist of and what are they used as?
- Ocular lens - eyepiece
- Objective lens - toward the object being viewed
What are the three types of telescopes? Briefly describe each.
- Refracting Telescope - consists of two lenses (objective and ocular) which gives higher resolution.
- Reflecting Telescope - Has a mirror for an objective instead of a lens, can be made very large which increases magnification.
- Combination Telescopes - Part refractor, part reflector.
Why aren’t planets in constellations?
Planets move in orbits so their positions are constantly changing.
Order the objects in the universe from biggest to smallest.
Universe, Galaxies, Constellations, Solar system, stars, planets, comets and meteors.
What are the two types of eclipses? Briefly describe each.
- Lunar - Earth is between the moon and the sun.
- Solar - Moon is between the earth and the sun.
What is spectroscopy?
The study of light refraction (bending).
What are spectroscopes used for?
These are used to help focus the spectrum produced by a prism.
What is Diffraction Grating?
A material that is split into several thousand tiny slits (bends light like a prism does but with better detail).
What are the three types of Spectra?
- Continuous
- Emission (bright line)
- Absorption (dark line)
What is spectral analysis?
A way of determining the composition of a star or light source. Remember, all lines must match for an element to be present.
What is the Doppler Effect?
A change in sound pitch caused by a change in the sound’s wavelength. Remember, short wavelength gives a higher sound but long wavelength gives a lower sound.
What is meant by the terms red end and blue end?
If a star is approaching the waves are compressed and shortened so the lines in the spectrum are shifted towards the blue end (blue is short). If a star is moving away the wavelength is lengthened so the lines in the spectrum are shifted towards the red end (red is long).
What are adaptive optics?
Computers that adjust mirrors to cancel atmospheric distortions.
What are the two units used for measuring space? How many astronomical units are in one light Year?
- Astronomical Unit (AU)
- Light Year - The distance light travels in one year.
There are 63 240 astronomical units in one light Year.
What is triangulation used for and what is it also known as?
Used to measure distances to unknown celestial objects. This is also known as parallax technique.
What are the steps in Triangulation?
- Distance of your baseline - The longer the baseline, the more accurate your calculations.
- Angle from one end of your baseline to the object (use a protractor).
- Angle from the other end of your baseline.
Remember, the baseline is the diameter of earth’s orbit around the sun. Two angles of the star are measured six months apart.
From previous one.
What are the types of Electromagnetic Radiation?
Light, infrared (heat), UV, x-rays, gamma rays, radio waves.
What is it called when you use radio waves?
Radio Astronomy.
