PHYS 1830 - Perspectives on the Universe Winter 2015 PLANETARIUM EXERCISE In this exercise, you will learn some of the stars that make up patterns in the sky. These are properly known as asterisms. Constellations, on the other hand, are defined as 88 regions or patches of sky that are officially designated by the International Astronomical Union (IAU). Constellations often contain the familiar patterns of stars that are the asterisms, but constellations are usually identified by their Latin name. For example, the asterism of the Big Dipper is contained within the constellation of Ursa Major, the Greater Bear. You will also be introduced to the astronomical coordinate system that is most commonly used to describe positions of objects in the sky: the equatorial coordinate system. Part 1: Sketching You will sketch several asterisms on a single page. Draw a line across the bottom of the page to indicate the position of the horizon. Label this line with the cardinal points. Draw a cross near the top of your sketch to represent the position of the zenith. Label this point. Lightly draw in the position of the meridian and label it. For each sketch, label the time for which the planetarium is set and record your location within the dome. Use circles to mark the relative positions of the stars. The size of the circle should reflect the relative brightness with larger circles indicating brighter stars. Use straight lines to connect the relevant stars to draw the asterism shape. Sketch #1: Big Dipper, Little Dipper, and Cassiopeia Label the asterism/constellation name. Label the pointer stars in the Big Dipper. Label Polaris. Sketch #2: Winter Hexagon (Orion, Taurus, Auriga, Gemini, Canis Minor, Canis Major) Include at least a few bright stars in each of the constellations and label each one. Label the seven brightest stars that make the hexagon (plus the middle): Rigel, Aldeberan, Capella, Castor, Pollux, Procyon, Sirius, and Betelgeuse, together with the Pleiades. Comment on the position of the the Big Dipper compared to your first sketch. Part 2: Equatorial Coordinate System Using the grid projected onto the planetarium, write down the equatorial coordinates of the following stars (Hint: remember that the great circles of RA converge on Polaris): Right Ascension (α) Declination (δ) Rigel Procyon Capella Pleiades Summer Solstice Tuesday, 20 January, 2015 -idc.