ASTR 205 Exam Study Guide

Scientific notation is used in science because - it makes it easy to write big or small numbers. The average distance from Earth to the sun is - 1 AU The sun is - a star 1 AU from Earth. more than 100 times the diameter of Earth. A galaxy contains - gas, dust, and stars, and a lot of dark matter. The Milky Way Galaxy - contains about 100 billion stars. 2.9×107 is the same as - . 29 million It takes light 1.3 seconds to travel from the moon to Earth and 8 minutes to travel from the sun to - The sun is 370 times further from Earth than the moon. If light takes 8 minutes to travel from the sun to Earth and 5 hours to travel from the sun to Pluto, whatis the distance from the sun to Pluto? - 37.5 AU The speed of light is 3.0×105 km/sec, and it takes light 1.3 sec for light to travel from the moon to Earth. From this information, what is the distance to the moon? - 390,000 km If the distance to the nearest star is 4.2 light-years, then a. the star is 4.2 million AU away. - the light we see left the star 4.2 years ago. The Milky Way Galaxy is - a spiral galaxy. part of a cluster of galaxies that contains a few dozen galaxies. about 75,000 light years in diameter. Which sequence is correct when ordered by increasing size? - Earth, Solar System, Milky Way, galaxy clusters How is a planet different than a star? - Planets reflect light while stars produce their own light If the distance from the Sun to the Earth is represent by roughly 15 meters, then the distance from the Earth to the Moon on the same scale would be - small than your hand. How is a planet different than a star? - Planets reflect light while stars produce their own light. Constellation names are in - latin Seen from the northern latitudes, the star Polaris - . is always above the northern horizon. The celestial equator is - a line around the sky directly above Earth's equator. the dividing line between the north and south celestial hemispheres. The ________ is the point on the celestial sphere directly above any observer. - zenith Most star names, such as Aldebaran and Betelgeuse are - arabic The magnitude scale - can be used to indicate the apparent intensity of a celestial object. The apparent visual magnitude of a star is a measure of the star's a. size. - intensity. The star Vega has an apparent visual magnitude of 0.03 and the star HR 4374 has an apparent visual magnitude of 4.87. It has been determined that both stars are at the same distance from Earth. What does this information tell us about the two stars? - Vega must produce more energy than HR 4374. The _______________ of an object depends on the diameter of the object and the distance to the object. - apparent diameter An observer's nadir is - the point directly opposite the observer's zenith. A(n) __________________ is one-3,600th of a degree. a. precession - second of arc The Big Dipper is - an asterism. . Precession of the rotation axis of Earth is caused by - the force of gravity from the sun and moon on Earth's equatorial bulge. An observer in the Northern Hemisphere watches the sky for several hours. Due to the motion of Earth, this observer notices that the stars near the north celestial pole appear to move - . counter clockwise around the celestial pole. You live at a latitude of 73° N. What is the angle between the northern horizon and the north celestial pole? - 73° . You live at a latitude of 39° S. What is the angle between the southern horizon and the south celestial pole? - 39° If the north celestial pole appears on your horizon, what is your latitude? - 0°