Titan

Titan is a moon of Saturn.  It is the only moon in the solar system known to have clouds and an atmosphere, and the only one with bodies of liquid on its surface.  The liquid is probably methane and ethane.

Length of a light-year

A light-year is approximately 5.8 trillion miles (or 9 trillion kilometers, if you are a scientist, or 9 trillion kilometres, if you are a British scientist).

Moon's diameter

The moon is approximately 283,000 miles, or thirty Earth diameters, away from Earth. If the Earth were a basketball, the Moon would be a tennis ball, a little less than a quarter the diameter.

Sirius

Sirius is the brightest star in the night sky (though not the closest), found in the constellation Canis Major.

It's seriously bright

A quasar is generally held to be the compact halo of matter surrounding the supermassive black hole at the center of a galaxy.

Ole Romer, a 17th century Danish astronomer, is believed to be the first to make quantitative measurements of the speed of light.

Dark energy, sometimes called dark force, is the hypothetical impetus behind the ever-increasing expansion of the universe.

Venus' surface temperature is 460 degrees Celsius (860 degrees F), making it the hottest planet. Its temperature far exceeds the melting point of lead.

Dione

Dione is a moon of Saturn, discovered in 1684. It is named for a Titan in Greek mythology.  It is believed to have a rocky core with ice.