$A$ Black Hole is:

$A$ total solar eclipse is observed from the Earth. At the same time,an observer on the Moon views the Earth. She is most likely to see ($E$ denotes the Earth):

The image shows a diagram of the solar system. Which of the following planets is known as the 'Red Planet'?

Assuming that the dimmest visible star to the naked eye has a magnitude of about $6$. The brightness of planet Venus (magnitude = $-4$) with respect to this star is ........ times brighter.

The tail of the comet is due to

How does the red shift confirm that the universe is expanding?