Over the next few weeks, Neptune will be approximately 2.7 billion miles (4.3 billion kilometers) from Earth. That is so distant that sunlight reflected off its icy cloud tops takes nearly four hours to reach us.

Shining at magnitude 7.8, Neptune is best seen through mounted binoculars or a backyard telescope. Start looking for the ice giant in the southeast sky in the constellation Aquarius, the water-bearer. You’ll find Neptune is now sitting about 3 degrees southwest of the fourth-magnitude star Lambda Aquarii. Scan the constellation carefully and look for a tiny blue-gray disk to pop out against a background of faint pinpoint stars.

The ice giant, shining at magnitude 5.7, is too faint to be seen with the naked eye, but