NATS 1745 Study Guide - Final Guide: Planetary Nebula, Radiography, Methods Of Detecting Exoplanets

• School: York University
• Department: Natural Science
• Course: NATS 1745
• Professor: Robin Kingsburgh

Document Summary

Shapley as big as our galaxy all of the spiral nebulae" lie inside our galaxy. Curtis spiral nebulae were distant separate entities, like our own galaxy. He discovered a cepheid in the andromeda spiral nebula, and calculated the distance at a few million light years much larger than anyone had anticipated they were island universes". Looking at stars at the edge of the galaxy. Astronomers measured the doppler shifts to calculate the rotation speeds of the stars. Calculated what the speed should be" based on the observed mass of the galaxy using newton"s laws. Expected: far from the centre of the galaxy speeds should be a lot lower than observed. To get large speeds the stars need to feel the pull of gravity from some kind of unseen material: A type of object that has a constant absolute brightness. Allows astronomers to get its distance vie the inverse square law.