One of the most beautiful objects in the night sky for amateur astronomers is the Pleiades star cluster.
A collection of young stars just being born, it is moving through the interstelllar medium of gas and dust, producing a wake in the interstellar medium, similar to a boat passing over water. Images of these wakes have been recorded by the IRAS (Infrared Astronomy Satellite) Orbiting observatory.
Unlike our sun, which is around 5 billion years old, the stars in the Pleiades star cluster are only about 50 million years old. The Pleiades star cluster is surronded by a cloud of dust and gas. The gas and dust are best seen on long exposure photographs. This cloud is seen not because it is glowing itself, but rather, merely from the reflection of the light created by the young proto stars. The haze looks blue for the same reason that the sky on Earth looks blue. The partcles of gas and dust comprising the haze around the Pleiades (like the molecules which make up our atmosphere) are in the correct size range to scatter blue light efficentlly.
Beneath the skies of Earth, You can only see the red and yellow parts of the spectrum when you look at the Sun itself. Hence, the familiar yellow/orange color you see as you glance (quickly!) at the Sun. Blue light, on the other hand, is scattered all over the sky, and can be seen in any direction we look. Therefore, the sky is blue, and so is the cloud around the Pleiades.
For those you who wondered what color the Sun would look above the scattering of Earth's atmosphere, the answer is still mostly yellow, but greener! Since the light which is making the sky appear blue most have come from the sunlight itself, before it entered the atmosphere, it was bluer. Almost green.
If you apply the principle that the wavelength of light emmited is determined by surface temperature (known in physics as Wein's law, and pronounced Veen's law), the color of the Sun should be.... yellow, almost green.
It does not appear that the stars in the Pleiades formed from the cloud of gas and dust which enshrouds it. Observations indicate that the stars are merely passing through this cloud of the interstellar medium. Some pictures have revealed wake trails left by the stars in their passing. Look for it a little over half way up the sky, towards the East/southeast at 8pm. It will rise to 2/3 of the way up the sky, facing to the south, by 10 pm. Look for it as a cluster of stars, all grouped together.
The Pleiades is commonly called the seven sisters, although only six at best are visible from our modern light polluted skies. In ancient times, it was a test of eyesight for roman soldiers to see the seventh star. It seems in those times, it was difficult at best to see the seventh star, but now it is impossible without some sort of optical aid. Some lovely views of the Pleiades may be seen with the aid of only a pair of binoculars. Try to use a pair with a large objective (main lens). This is the second number which can be read on a pair of binoculars (as in 10X50, or 7X35). Around 50 mm is the nminimum to use for astronomy. A telescope will reveal more detail in the core of the Pleiades, but you cannot see as large of an area at one time.
Clear skies, and good viewing.
