Category

Research of Environment of Night Sky

ntroduction

Check out the darkness of night sky in your local area and see how much it is affected by Light Pollution.

　Dark Sky Meter is a device that can show the brightness (or darkness) of the night sky by the numerical value by comparing the brightness of the night sky with the brightness of the light emitting diode of the night sky meter. The difference of the brightness of the night sky according to a lot of points, directions, and time can be compared with this device.
　Determine the darkness of night sky by Dark Sky Meter and think about the night sky environment and see how much it is affected by Light Pollution.

The Visibility of a Star and Darkness of Night Sky

　Where can you see more stars, in the town with a less dark night sky, or in the mountains with a darker night sky?
　You can see something bright in a dark place more easily than in a bright place. For example, when you are looking for a room light on by seeing windows of the building from outside, which is easier, looking for it in the daytime or the evening? Because it is bright outside in the daytime, it is difficult to distinguish a bright window from outside. You can easily distinguish a bright window from dark outside when it is evening. Something similar happens between the night sky and stars. Light from a star is much fainter than a building window, so recognizing it is more difficult. If the night sky is not dark enough,faint stars can not be seen well any more.
　We can work and live more safely at night with artificial lights, on the other hand, more and more night sky get too brighter by too many lights, so we can not see a lot of stars(Light pollution) .

How to use Dark Sky Meter

Experimental Method

Things to prepare

Torch with red film (Or, you can paint the light side with red paint. )、Pen and pencil set、Observing Report Sheet、Dark Sky Meter、Compass、Star map

Research point

　It is the best that you measure from the place where you live normally. If possible, it is best if you have a clear view of most of the sky from there.

Weather of the research day

　A clear day without any cloud is the best, however, you will not have many observations if you wait on such a fine day. Just take notes on the observing report sheet like "In the eastern heavens thin clouds" when there is a cloud.

Research directions of the sky

　Make observations at the zenith and in the directions north, south, east and west at ten degrees altitude, using standard stars such as the Pole Star, Mizar, the Cassiopeia γ, Vega Altair Deneb, the Pegasi α, Fomalhaut, Aldebaran, Capella, and the Arietis α and record your observations on the Observing Report Sheet.
When you can not measure all the directions, just check the direction of zenith.
You can measure "The ten degrees" of north, south, east, and west like this: when you stretch out your arm and clench your fist, when your little finger is level with the horizon, then the thumb becomes about ten degrees. Moreover, when peeping through the Dark Sky Meter, the field of view of the scope is about seven degrees from one side to the other.

Before the research

　Sit in a darkened area for a while, to allow your eyes to become dark-adapted.
When you need light to write the results on paper or to see a star map, use a red light torch.

Dark Sky Meter Project

Dark Sky Meter Project