The moon is full tonight, and it helps us locate Jupiter, which rises slightly before the moon and sits just to the right, or south, of it.
Because Jupiter is so bright, it should not be overwhelmed by the moon, and the two of them will be a splendid sight. Look for them above the eastern horizon starting around 7:30 p.m.
For a tougher challenge, look toward the southeast at 8 p.m. or later and try to find Fomalhaut, the bright star that rises slightly later than the moon and Jupiter and will be a little closer to the horizon. Fomalhaut is the 18th-brightest star in the sky and is easily visible on a dark night.
On this day in 1846 at the Berlin Observatory, Johann Gottfried Galle (1812-1910) discovered Neptune. He used calculations of Urbain Le Verrier (1811-77), who predicted an outer planet beyond Uranus due to small variations between the predicated position for Uranus and its actual observed position.
Similar slightly earlier calculations were performed by British astronomer John Couch Adams (1819-92), and there has been a lingering controversy as to who should get the credit for the discovery of Neptune.
Nowadays, the credit is generally given to all three astronomers, though it is actually Galle, with his assistant, Heinrich Louis d'Arrest (1822-75), who first recognized Neptune through a telescope.
Neptune is a giant planet exceeded in mass only by Jupiter and Saturn. It is too far away to be seen without an optical aid. Through a small telescope, Neptune looks like a tiny blue or blue-green disc. Neptune has 17 times the mass of the Earth and a diameter nearly four times that of the Earth. It is the farthest planet from the sun now that Pluto is no longer considered a full-fledged planet.
Contact Tim Hunter at firstname.lastname@example.org