Overview

In this section you will find materials that support the implementation of EarthComm, Section 2: Locating Astronomical Objects in the Night Sky.

Learning Outcomes

• Develop a model for identifying specific locations on Earth.
• Analyze a coordinate system as a mathematical model for locating objects in the sky.
• Identify patterns in the organization and distribution of matter in the universe.

Using Technology

To learn more about locating objects in space, complete the following:

Exploring the Celestial Sphere

1. In the previous section, you examined a sky map using the Google Earth software program. Google Earth enables you to explore the celestial sphere using a coordinate system. You can also look into the night sky and observe astronomical objects from various directions and from different locations on the Earth’s surface. Using a computer with an internet connection, open Google Earth. If your computer does not have Google Earth installed, go to http://earth.google.com/ to download a free version.
2. Under the “Fly To” tab in the “Search” panel, type in the name of your town or city and state and then click the hand icon. Google Earth will zoom into your location.
3. Click the thumb tack icon on the toolbar to put a placemark on your location. Insert the name of your location and make a note of its longitude and latitude.
4. Click the planet icon on the toolbar and select “Sky.” In the “Places” panel click on your location. Use the zoom slider navigation control to zoom out from your location. You should now see a view of the night sky from your location on the Earth.
   1. Describe what you see.
   2. What constellations are visible from this location?
5. Return to a view of the Earth by clicking on the planet icon and selecting “Earth.”
6. Determine the location in the southern hemisphere that is exactly opposite your own. Use the navigation controls and lines of longitude and latitude to help you find this location. Click the thumb tack icon on the toolbar to put a placemark on this location. Give this location a name.
7. Return to a view of the sky by clicking on the planet icon on the toolbar and selecting “Sky.” Use the zoom slider navigation control to zoom out from your new location. You should now see a view of the night sky from your new location.
   1. How does the view from your southern hemisphere location compare to the view from your northern hemisphere location?
   2. What constellations are visible from this location?
8. Chose four other places on Earth and explore the night sky from each. Record the constellations visible from each location.
9. Return to a view of the Earth. Go to where the Prime Meridian intersects the Equator. Placemark this location and record its coordinates. View the night sky from this location.
   1. What do you notice about the values of the celestial sphere grid coordinates at this location?
10. Lines comparable to latitude on Earth are called declination on the celestial sphere. Positions north of the celestial equator are called plus declination and are measured in degrees. Positions south of the celestial equator are called minus declination and are also measured in degrees. The lines that correspond to longitude on Earth are called right ascension. Right ascension is measured from the point where the Sun crosses the celestial equator about March 21 (the vernal equinox). Right ascension is measured in hours, minutes, and seconds, moving eastward from the vernal equinox. Use the navigation controls to go locate the place in the night sky where the declination and right ascension have zero values.
    1. What is the closest star to this position?
11. Using the navigation controls, orient the celestial sphere towards the north celestial pole. Find Polaris, the North Star, and record its coordinates and the name of its constellation.
12. Using the navigation controls, orient the celestial sphere towards the south celestial pole. Find the Southern Star and record its coordinates and the name of its constellation.
13. In the “Layers” panel, click on “Featured Observatories.” In the sky view, click on the “Featured Observatories Introduction.” This should bring you to a list of programs and satellites used by scientists to research astronomical objects and celestial phenomena. Learn more about each observatory by clicking on its name.
14. Use the “Featured Observatories” to explore the Universe. Find and record the names, coordinates, and the nearest constellation for the following:
    1. Two different types of galaxies
    2. A black hole
    3. A super nova
    4. A gamma burst
    5. The largest star in the Milky Way Galaxy
    6. A region with new stars being born
15. In the “Layers” panel, click on “Our Solar System.” In the sky view, go to the “Solar System Introduction.” Follow the directions provided for finding the location of a planet at a particular time. Find and record the coordinates and the nearest constellation for the following:
    1. Jupiter today
    2. Jupiter one week from today
    3. The Moon today
    4. The Moon one week from today

Inquiring Further

1. To learn more about Earth’s axial tilt and the position of Polaris, visit the following web sites:
   
   Polaris, Lunar and Planetary Institute
   Provides information about Polaris, including the effect of the wobble of Earth’s axis.
   
   Milankovitch Cycles and Glaciation, Indiana University
   Provides information on variations in the Earth's eccentricity, axial tilt, and precession.
   
   Precession, NASA
   Learn how the north star can change as the Earth wobbles on its axis.
    
2. To learn more about how to use star charts, visit the following web sites:
   
   Your Sky Tonight, PBS
   Create a star chart set for your time and location.
   
   The Night Sky This Month, Emil Neata
   Learn where to locate planets, comets and meteors in the night sky.
   
   This Week's Sky at a Glance, Sky and Telescope
   Learn more about daily events in the changing sky.
   
   Astronomy: Your Sky Tonight, PBS
   Enter your zip code to bring up a star chart of your local area.
    
3. To learn more about constellations , visit the following web site:
   
   The Constellations, International Astronomical Union
   A comprehensive list of the 88 defined constellations with official spellings and abbreviations.

Resources

To learn more about this topic, visit the following web sites:

The Celestial Sphere, NASA
Learn how the sphere of the sky has two points around which it turns, points that mark its axis - the celestial poles.

Changes in Star Positions, NASA
Find out why stars seem to travel across the sky at night differently than the moon moves?

Animations and Video

To view animations and video related to this topic, visit the following web site:

Video: Using Star Charts and Star Wheels, Sky and Telescope
Video that explains how to use sky charts and star wheels.