Between two objects is directly proportional to the

between two objects is… ▷Directly proportional to the product of their masses ▷Inversely
proportional to the square of the distance between their centers (gravitational force = 1/d^2)
 Every star is part of a constellation
 Three powers of telescopes ▷Collect more light than our eyes  Light-gathering power
▷See more detail data than our eyes  Resolving power ▷Enlarge images  Magnifying power
 The resolution of a telescope is a measure of its ability to differentiate between close objects or discern small
details of an object
 Area = pi*(d/2)^2
 Why do astronomers like big telescopes? ▷Light gathering power improves with area of primary mirror i.e diameter2
▷Resolving power improves with diameter of primary mirror
 Why do astronomers put telescopes on mountains? ▷Telescope sites are chosen to minimize the problems of light
pollution, atmospheric turbulence, and bad weather. Why do we put telescopes into space? ▷Forms of light other than
radio and visible do not pass through Earth’s atmosphere ▷Also, much sharper images are possible because there is no
turbulence
 What is angular resolution of a telescope? ▷The smallest angular separation that two point-like objects can have and
still be seen as distinct points of light (rather than as a single point of light)
 What is angular size? ▷A measure of the angle formed by extending imaginary lines outward from our eyes to span an
object (or the space between two objects)
The Sun and Seasons (for finding rise/set, find where it usually would be, and that’s the middle)
 Perihelion (Near sun) Aphelion (Far from sun) ▷In general, the sun rises in the east and sets in the west
 Summer (June) solstice – when the Northern Hemisphere is tipped most toward the Sun (rises due north)
 Winter (December) solstice – the Northern Hemisphere is tipped most away from the Sun (rises due south)
 Spring (March) equinox – Northern Hemisphere starts to be tipped toward the Sun (rises due east)
 Fall (September) equinox – Northern Hemisphere starts to be tipped away from the Sun (rises due east)
Eclipses
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