Distance in Space

Light Years 0 Light years is a measurement in distance, not a measurement of time. 0 Light year represents the distance that light travels in one year. 0 Light from the Sun takes approximately 8 minutes (or 480seconds) to get to Earth; and 1 AU (distance Sun is to Earth) is 149,597,871 km. 0 Thus 149,597,871 km = 311, km/s 480s 0 Lets round that and say that the speed of light is 3.0 x 10 5 km/s

Light Years 0 If light travels 3.0 x 10 5 km/s, how far does it travel in one year? 0 (60s/m)(60m/hr)(24hr/days)(365 days/year) = 31,536,000 s/year Thus: 3.0 x 10 5 km/s (31,536,000 s/year) One Light Year = 9.5 x km/year

Measuring Distance in Space 0 The volume of the universe is 1.0 x cubic light years. Hence, we assume the universe is 3-D and we can measure, approximately, how big our universe is. 0 Scientists have a multitude of ways to measure distance in space, but because we cannot just lay a ruler down and measure distances we need to use complex mathematical equations. 0 The three ways we will learn to measure distance in Space is : 1) Parallax, 2) Baselines, and 3) Red Shifts.

Parallax 0 Parallax is measuring the apparent motion of a nearby star against the background of a more distance non- moving star. 0 We measure a parallax in parsec, 1 parsec is 3.26 light years. 0 Use example from pg 420

Baselines 0 Scientists use a baseline to create a triangle and use trigonometry to solve the distances things are. The angle of Earth to Saturn is 84 degrees. The baseline distance from the Sun to Earth is 3.0x10 8 Draw a straight line up from the sun you will see it creates a triangle. Solve for the distance to Saturn.

Red Shifts 0 As discussed earlier, the farther we are from an object, the more the light waves move from the violet to the red part of the light spectrum. 0 Notice theline on the light spectrum shifts the further we get from the star we are looking at:

Sample Problem #1 0 Page Assignment – Page 424, Questions 2, 3, 16 and 17