Optical Double Galaxies The galaxies M81 and M82 (Figure XXXXXXXXXXappear to be near each other, as seen on photographs taken from the Sun. In this exercise, you can use Starry Night Enthusiast™ to...

Optical Double Galaxies The galaxies M81 and M82 (Figure 16-25) appear to be near each other, as seen on photographs taken from the Sun. In this exercise, you can use Starry Night Enthusiast™ to determine just how close they are in space. Select Favourites
 Deep Space
 Galaxies
 M81 and 82 from the menu. Click the Stop button to stop time flow. The view, covering a field only 1° wide, is centered on M81, also called Bode’s Galaxy. To the right is M82, also called the Cigar Galaxy. Note particularly the difference in appearance of these two galaxies. Use the angular measurement tool to determine the angular distance separating these galaxies, as seen from Earth. Compare this separation to the apparent size of the Full Moon (about 30 in diameter). To find the actual physical distance separating these two galaxies, select Favourites
 Deep Space
 Galaxies
 Local Universe from the menu. This view shows the Milky Way and several nearby galaxies against a background of more distant galaxies. Open the Find pane and type “M81” in the search box without pressing the enter key. In the list of objects found, click the “” button immediately left of the label for M81. Then double-click the bottom entry in the expanded list for M81, labeled Spiral Sab Galaxy under the “Kind” heading, to center this galaxy in the view. Type “M82” in the search box of the Find pane without pressing the Enter key. Expand the list for M82 and click the box to the left of the bottom entry to label this galaxy. Zoom in to a field of view 1° wide. Again use the angular measurement tool to measure the distance between these two galaxies. The actual distance separating the galaxies is indicated in blue below their angular separation as seen from this observing position. Are these two galaxies as close to each other as the Milky Way and the Large Magellanic Cloud, which are about 0.195 Mly apart?