Deep Sky Objects Help


    The settings in this view let you control the display of star cluster, nebulae, and galaxies - including the selection of deep sky objects that are shown, and the labelling of objects with their names or catalog numbers.

    Deep Sky Object Display

    Show Objects: Draws symbols for star clusters, nebulae, and galaxies in the sky chart. When turned off, most of the other settings in this view are disabled.

    Show Images: Displays images of deep sky objects in the sky chart. When turned on, Digitized Sky Survey images of several hundred best-known deep sky objects are drawn at their true size and orientation in the sky chart. Deep sky images can be displayed independently of deep sky object symbols (above), and vice-versa.

    Best-Known Only: Sets whether only the best-known deep sky objects are shown in the sky chart. These objects include the Messier objects, the Caldwell objects, and any other deep sky objects with a proper or common name.

    • The Messier Catalog is a famous list of 110 prominent deep sky objects compiled by the 18th century astronomer Charles Messier. The Messier catalog includes some of the most prominent star clusters, nebulae, and galaxies visible from the northern hemisphere, such as the Hercules Cluster (M 13) and the Whirlpool Galaxy (M 51).

    • The Caldwell Catalog is a modern complement to Messier's list, compiled in 1995 by the British astronomer Patrick Caldwell-Moore. It includes additional 110 "Messier-quality" deep sky objects which Messier missed, many because they are only observable from the southern hemisphere. Together, the Messier and Caldwell lists include most of the deep sky objects easily visible in backyard telescopes from both hemispheres.

    Please Note: this feature is only available in the SkySafari Plus and Pro.

    Show in Wide Fields: allows deep sky objects to be displayed when the field of view is wider than 45 degrees. This option is turned off by default, since deep sky objects can only be seen through binoculars or telescopes, which have very small fields of view. However, turning this option on may let you see the distribution of (for example) galaxies across wide areas of the sky.

    Please Note: this feature is only available in SkySafari Plus and Pro.

    Magnitude Limit: Sets the deep sky object magnitude limit. This determines the faintest deep sky objects that are visible in the sky chart. The brighter an object, the lower its magnitude. The magnitude limit will change automatically as you zoom the sky chart in and out. When zoomed in, fainter objects are displayed.

    Never Show Fainter Than: This sets the absolute magnitude limit of the faintest deep sky objects visible. When you zoom in, objects fainter than your set limit are never displayed.

    Intensity: Sets the brightness used to display deep sky object symbols and names. Move the slider to vary the brightness from 0% (black) to 100% (white).

    Deep Sky Object Name Display

    Show Names: Sets whether deep sky objects' names are displayed next to the objects in the sky chart.

    Proper Names: Sets whether proper names are displayed for deep sky objects, when possible. When turned off, deep sky objects names are always shown using catalog numbers (e.g. "M 13") instead of proper names (e.g. "Hercules Cluster").

    Name Density: Sets the percentage of deep sky objects whose names are displayed on the sky chart. At 0%, no objects have names shown; at 100%, all objects have names shown. At 80%, the brightest 80% of deep sky objects have names shown.

    Deep Sky Object Type Selection

    Please Note: this section is only available in SkySafari Plus and Pro.

    Globular Clusters: Sets whether globular clusters are displayed in the sky chart. These are dense concentrations of stars, typically containing tens of thousands to millions of stars. These massive clusters are among the oldest objects in our galaxy. Examples are M 13 in Hercules and M 22 in Sagittarius.

    Bright Nebulae: Sets whether bright nebulae are displayed in the sky chart. These are glowing clouds of gas usually found in the disk of the Milky Way. These nebulae glow either from the reflection of light from nearby stars or from the emission of light produced by nearby stars heating the nebulae. Examples are M 42 (the Great Orion Nebula) in Orion and M 20 (the Trifid Nebula) in Sagittarius.

    Dark Nebulae: Sets whether dark nebulae are displayed in the sky chart. These are opaque clouds of cold dust which obscure the light from the stars behind them. They are mostly located along the Milky Way. Examples are B 33 (the Horsehead Nebula) in Orion, and the Coal Sack in Crux.

    Planetary Nebulae: Sets whether planetary nebulae are displayed in the sky chart. These are expanding shells of gas expelled from a star late in its life. A round, planet-like appearance led to the name "planetary nebulae" in the eighteenth century, though there is no actual connection with planets. Examples are M 57 (the Ring Nebula) in Lyra and M 27 (the Dumbbell Nebula) in Vulpecula.

    Galaxies: Sets whether galaxies are displayed in the sky chart. Galaxies are immense star systems outside of our own Milky Way galaxy; many are larger than our own. The total number of galaxies is in the billions, and they extend to the edge of the known universe. Most galaxies are classified as spiral galaxies, elliptical galaxies, or irregular galaxies, based on their appearance. Examples are M 31 (spiral) in Andromeda, M 87 (elliptical) in Virgo, and the Small Magellanic Cloud (irregular).