The screenshot attached show the double circle mark on Celestial Equator. It is very close to RA zero hours, but not quite!
Wondering what this mark means?

The screenshot attached show the double circle mark on Celestial Equator. It is very close to RA zero hours, but not quite!
Wondering what this mark means?

You have enabled "Earth & Moon Shadow Circles" in the Solar System settings. This shows the Earth's shadow projected into space at the Moon's distance. Useful for visualizing a lunar eclipse. During the eclipse, the Moon will move into the circles.
ah OK, thanks Bill.