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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