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The Sloan Digital Sky Survey camera has five filters.
Filters are pieces
of glass that let in only certain colors of light. So the camera sees
every sky object in five colors.
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The SDSS camera's
five filters |
The first filter is u, or ultraviolet. Ultraviolet light is the invisible
light that causes sunburns. The next two filters are green and red,
called g and r. These are colors you see every day. The last two
filters are "infrared light" filters called i and z. You can't see
infrared light, but you can feel it as heat from a stove or
fireplace.
The brightness of a sky object is called its magnitude. The higher the magnitude,
the fainter the object! That scale might seem backwards to you, but
astronomers have used it for thousands of years.
You can use SkyServer's Navigation tool to look up the magnitude for any
of SkyServer's 150 million objects. Click Next to find out how.
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