The Sky

Views:
 
Category: Entertainment
     
 

Presentation Description

No description available.

Comments

Presentation Transcript

The Sky : 

9/25/2008 The Sky 1 The Sky Edward M. Murphy Space Science for Teachers 2005

Horizon and Zenith : 

9/25/2008 The Sky 2 Horizon and Zenith It is sometimes useful to think of the sky as a great dome over our heads. The horizon is where the dome meets the Earth. The zenith is the point directly overhead. As the Earth turns, this dome turns over our heads. It appears as if the sky is a large hollow sphere centered on the Earth.

Horizon and Zenith : 

9/25/2008 The Sky 3 Horizon and Zenith

Altitude and Azimuth : 

9/25/2008 The Sky 4 Altitude and Azimuth The height of a star above the horizon is called the altitude. The direction to the star as measured from true north is called the azimuth. Note: True north is not the same as magnetic north. The magnetic north pole is not located in the same place as the true north pole. On maps, the legend will show you how to correct from magnetic north, as measured by a compass, to true north.

Altitude and Azimuth : 

9/25/2008 The Sky 5 Altitude and Azimuth

Magnetic North Pole : 

9/25/2008 The Sky 6 Magnetic North Pole

Magnetic North : 

9/25/2008 The Sky 7 Magnetic North

Correction from Magnetic North to True North : 

9/25/2008 The Sky 8 Correction from Magnetic North to True North

Altitude and Azimuth : 

9/25/2008 The Sky 9 Altitude and Azimuth The altitude and azimuth of a star change during the course of night as the star rises and sets. Angles are measured using degrees, minutes of arc, and seconds of arc.

Measuring Angles in the Sky : 

9/25/2008 The Sky 10 Measuring Angles in the Sky

Measuring Angles : 

9/25/2008 The Sky 11 Measuring Angles Angles in astronomy are measured in degrees, arcminutes and arcseconds. 1 degree = 60 arcminutes 1 arcminute = 60 arcseconds 1 degree = 3600 arcseconds 1 arcsecond is the size of a U.S. quarter as seen from 5 km (3 miles) or a penny as seen from 2.2 miles.

Measuring Angles : 

9/25/2008 The Sky 12 Measuring Angles The Sun and Moon appear to be about ½ degree in size. Your finger held at arms length is about one degree across. Your fist at arms length is about 10 degrees. Your outstretched hand at arms length is about 20 degrees across.

Angular Sizes and Distances : 

9/25/2008 The Sky 13 Angular Sizes and Distances

The Celestial Sphere : 

9/25/2008 The Sky 14 The Celestial Sphere

The Celestial Sphere : 

9/25/2008 The Sky 15 The Celestial Sphere

The Celestial Sphere : 

9/25/2008 The Sky 16 The Celestial Sphere North Celestial Pole: The point directly over the Earth’s true north pole. The north star, Polaris, is near the North Celestial Pole, but not exactly at the pole. It is currently about 1 degree away from the pole. South Celestial Pole: The point directly over the Earth’s true south pole. Celestial Equator: The equator of the Earth projected onto the celestial sphere. Meridian: A line from due north to due south that passes straight overhead.

Longitude and Latitude : 

9/25/2008 The Sky 17 Longitude and Latitude

Longitude and Latitude : 

9/25/2008 The Sky 18 Longitude and Latitude Latitude: Your north-south position on Earth. The equator is defined to have a latitude of 0o. The north pole is at 90oN and the south pole at 90oS. Longitude: Your east-west position on Earth. An arbitrary point, the Prime Meridian in Greenwich, England marks a longitude of 0o. Leander McCormick Observatory is at: Longitude 78o 31’ 19.8” W Latitude 38o 01’ 58.2” N Altitude 264 meters

Rotation of the Earth : 

9/25/2008 The Sky 19 Rotation of the Earth

Slide 20: 

9/25/2008 The Sky 20 The stars move from east to west because the earth rotates from west to east.

The Motion of the Stars : 

9/25/2008 The Sky 21 The Motion of the Stars Just like the Sun and Moon the stars rise and set due to the rotation of the Earth. They rise in the east and set in the west because Earth rotates from west to east. Stars near the celestial poles do not rise or set. Instead they circle the poles and are called circumpolar. In the northern hemisphere, the stars circle the pole in a counterclockwise direction.

Daily (Diurnal) Motion of the Stars : 

9/25/2008 The Sky 22 Daily (Diurnal) Motion of the Stars

Circumpolar Stars : 

9/25/2008 The Sky 23 Circumpolar Stars

Diurnal Paths of Stars : 

9/25/2008 The Sky 24 Diurnal Paths of Stars

Diurnal Paths of Stars : 

9/25/2008 The Sky 25 Diurnal Paths of Stars

Diurnal Paths of Stars at Intermediate Latitude : 

9/25/2008 The Sky 26 Diurnal Paths of Stars at Intermediate Latitude

Celestial Poles : 

9/25/2008 The Sky 27 Celestial Poles

North Celestial Pole : 

9/25/2008 The Sky 28 North Celestial Pole In the northern hemisphere, the altitude of the north celestial pole is equal to your latitude on Earth. This is useful for navigation. If you measure the altitude of the north celestial pole, you can determine your latitude on Earth. In the southern hemisphere, it is difficult, but not impossible, to find the location of the south celestial pole.

Diurnal Paths of Stars at Intermediate Latitude : 

9/25/2008 The Sky 29 Diurnal Paths of Stars at Intermediate Latitude

Celestial Sphere : 

9/25/2008 The Sky 30 Celestial Sphere To find due north, drop straight down from the North Celestial Pole to the horizon. The celestial equator meets the horizon at due east and due west.

Diurnal Paths of Stars : 

9/25/2008 The Sky 31 Diurnal Paths of Stars

Celestial Sphere Movie : 

9/25/2008 The Sky 32 Celestial Sphere Movie http://brahms.phy.vanderbilt.edu/~rknop/astromovies/

Celestial Coordinates : 

9/25/2008 The Sky 33 Celestial Coordinates Just as Earth has lines of longitude and latitude, the celestial sphere has a system of celestial coordinates: Declination (dec): The north-south position of a star on the celestial sphere. Declination is measured in degrees, arcminutes, and arcseconds. The celestial equator is defined to have a declination of 0o. Right Ascension (RA): The east-west coordinates of an object on the celestial sphere. R.A. is measured in hours, minutes, and seconds of time. The vernal equinox is defined to be 0h.

Celestial Coordinates : 

9/25/2008 The Sky 34 Celestial Coordinates

Celestial Coordinates : 

9/25/2008 The Sky 35 Celestial Coordinates Vega RA 18h35m DEC +38o44’

Slide 36: 

9/25/2008 The Sky 36

Slide 37: 

9/25/2008 The Sky 37

Slide 38: 

9/25/2008 The Sky 38

Classroom Exercise : 

9/25/2008 The Sky 39 Classroom Exercise Find Orion in the night sky. Is it on the equator, the ecliptic, both, or neither. How long is Orion above the horizon each day? Find Sagittarius. Is it north or south of the equator? How long is Sagittarius above the horizon each day?

Classroom Exercise : 

9/25/2008 The Sky 40 Classroom Exercise Find Taurus. Is it north or south of the equator? How long is it above the horizon each day? Find the Sun on December 21. Which constellation is it in? How long is it above the horizon each day? Find the sun on June 21. Which constellation is it in? How long is it above the horizon each day?

authorStream Live Help