Activities

Observing Projects

  1. Use Starry Night to make observations of the solar system. Select Favourites > Explorations > Solar System. The view shows the names and orbits of the major planets of the solar system against the backdrop of the stars of the Milky Way Galaxy, from a location hovering 64 AU from the Sun. You may also see many smaller objects moving in the asteroid belt between the orbits of Mars and Jupiter. (If not, select View > Solar System and click on the Asteroids box.) (a) Use the location scroller to look at the solar system from different angles, and observe the general distribution and motion of the major planets. Make a list of your observations. (b) How does the nebular hypothesis of solar system formation account for your observations?

  2. Use Starry Night to examine stars that have planets. Select Favourites > Explorations > Extrasolar Planets. This is the view of nearby space looking back toward the location of Earth from a distance of about 90 light-years. Use the location scroller to look around. Stars marked with a light blue halo show evidence of having at least one planet. Right-click (Ctrl-click on a Mac) on a sample of these circled stars and select Show Info from the contextual menu to learn more about the star’s properties. Under the Other Data layer, note the star’s apparent magnitude, which is a measure of how bright each star appears as seen from Earth. Apparent magnitude uses an inverse scale: The greater the apparent magnitude, the dimmer the star. Most of the brighter stars you can see with the naked eye from Earth have apparent magnitudes between 0 and 1, while the dimmest star you can see from a dark location has apparent magnitude 6. Also note, under the Other Data layer info for your sample stars, the extrasolar mass (the mass of the extrasolar planet) and extrasolar semimajor axis (a measure of the planet’s distance from its parent star). (a) Are most of the circled stars in your sample visible to the naked eye from Earth? List at least two stars that have extrasolar planets that are visible to the naked eye from Earth and include their apparent magnitudes. Expand your sample if necessary. (b) Are most of the planets in your sample larger than Jupiter? Offer a hypothesis to account for this. (c) You may have noted that a surprising number of extrasolar planets in your sample are both very massive and also orbit very close to their parent star. What hypothesis might account for this?

  3. Use Starry Night to investigate stars that have planets orbiting them. Click the Home button in the toolbar. Open the Options pane and use the checkboxes in the Local View layer to turn off Daylight and the Local Horizon. Expand the Stars layer in the Options pane and then expand the Stars item and check the Mark stars with extrasolar planets option. Then use the Find pane to find and center each of the stars listed below. To do this, click the magnifying glass icon on the side of the edit box at the top of the Find pane and select Star from the dropdown menu; then type the name of the star in the edit box and press the Enter or Return key on the keyboard. Click on the Info tab for full information about the star. Expand the Other Data layer and note the luminosity of each of these four stars: 47 Ursae Majoris (3 known planets); 51 Pegasi (1 known planet); 70 Virginis (1 known planet); Rho Coronae Borealis (1 known planet). (a) Which stars are more luminous than the Sun? (b) Which are less luminous? (c) How do you think these differences would have affected temperatures in the nebula in which each star’s planets formed?