Telescopes

• The most important functions of a telescope is to collect light and focus it into an image

• The light collected can range over the entire electromagnetic spectrum

• Telescopes that focus visible light are called optical telescopes

• »Why is the star Polaris important in sky observations? Polaris is the star in the center of the star field

• »What is the difference between rotation and revolution? "Rotation" refers to an object's spinning motion about its own axis. "Revolution" refers the object's orbital motion around another object.

• »What are the values of the Earth and Moon’s rotation and revolution? The reason that the same side of the Moon always faces the Earth is that the Moon rotates on its axis in the same period of time

• Keplers 3 laws: 1) every planet’s orbit is an ellipse with the Sun at a focus; 2) a line joining the Sun and a planet sweeps out equal areas in equal times; and 3) the square of a planet’s orbital period is proportional to the cube of the semi-major axis of its orbit. As it’s the third which is most often used, Kepler’s law usually means Kepler’s third law (of planetary motion).

• Relative to an ellipse, what does eccentricity define? The eccentricity of an ellipse is, most simply, the ratio of the distance between the center of the ellipse and each focus to the length of the semi major axis a

• Where on an ellipse would you find perihelion and aphelion?   draw a diagram of saturn’s orbit which is an ellipse and place the sun at one of the foci

• What does perihelion measure? Perihelion measures the point of the earths orbit closest to the sun

• What does aphelion measure? earths furthest point from the sun

• Why do we have seasons? the earths tilt

• What direction is the Earth’s axis pointing during our summer?  Towards the sun

• What direction (away or toward the Sun) is the Earth’s axis pointing during our (the northern hemisphere’s) winter?  away from the sun

• Which direction is the Earth’s axis pointing during Australia’s summer?  towards the sun

• Which direction is the earths axis facing during Australia's winter? away from the sun

• Why is Australia’s summers and winters more extreme than ours (the northern hemisphere’s)? Because the location make the sun rays more direct on the continent

• Describe how the light received by the Arctic change over a year.  Light is either received at all times and it is bright for the majority of the day or it is dark and the light they get is very minimal

• Summer solstice? Longest day of the year

• Winter solstice? Shortest day of the year

• Vernal Equinox? Sun crosses the equator

• Autumnal Equinox? Sun crosses the celestial equator going south

• What are 8 phases of the moon? Full moon, Waining Gibbous, 3rd quarter, waxing crescent, new moon, waxing crescent, First Quarter, waxing gibbous