27 January 2007

The Sun, Mercury & Venus

Date: 26 January 2007 U.T.
Time: 18:02 - 19:00 U.T.
Telescope: 13cm Refractor
Magnifications: 80x and 110x
Seeing: Poor
NELM: Daytime
Temperature: +33 F (+1 C)


The above sketch shows a sunspot that has just rotated onto the Earth-facing side of the Sun. North is up. Preceding (west in the sky) is to the left. Both sketches appearing in this post are mirror-reversed. Notice that the spot's umbra appears off-set toward the center of the Sun. Sunspots near the solar limb often show this "Wison effect."

The brighter patches near the sunspot are faculae. Faculae show up best near the solar limb where limb-darkening darkens the surrounding area.

A safe, white-light, solar filter was placed over the telescope's objective for this observation.


The above sketch shows Mercury (to the left) and Venus. North is up. Preceding is to the left. The thin, unlit portions of the planets were invisible; but in the sketches those areas appear darker than the background sky. I decided to depict the planets in this manner after seeing how difficult it was to notice the phases in my previous Mercury - Venus sketch. Venus was a tad bit closer to being full than the above sketch suggests. There's always something that isn't quite right; but usually I don't say anything!

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