View Full Version : Shape of Pleiades

2012-Jan-05, 03:22 PM
Pleiades are 120...140 parsecs away - uncertainty of 20 parsecs.

In the direction along solar sky, Pleiades are nearly 2 degrees across - meaning about 4 parsecs.

Pleiades might be expected to have some extent in direction to Sun (rather than being a completely spherical sheet focused on Sun). But any thickness of Pleiades is likely to be much less than the uncertainty in distance.

Is there any way at all to tell which are front and which are rear Pleiades? Such as based on the light and shadows which the Pleiades cast on their nebula?

2012-Jan-05, 03:37 PM
If you can wait the better part of a decade, Gaia data will just tell you. Aside from that, your shadows idea could work in thicker nebulae, so I imagine with a lot of work, and a lot of light gathering power, you might be able to make good guesses. Proper motion studies might also give you some good guesses.