Five planets in our solar system are easily visible in the night sky with the unaided eye. Currently, Jupiter, Mars and Saturn are easy to spot in the evening sky. As Venus and Mercury are both emerging from behind the Sun in mid-July, they can be seen with some difficulty low in the western twilight just after sunset. Because all these planets are relatively bright, it is not difficult for sky watchers on Earth to notice their apparent motion among the stars from night to night. Therefore, all these planets have been known since antiquity.
In contrast, the two outermost planets, Uranus and Neptune are so far from the Sun, and reflect so little light to Earth that their existence was not revealed until after the invention of the telescope. Uranus, which orbits twice as far from the Sun as Saturn was discovered on March 13, 1781. Neptune was discovered sixty five years later in 1846.
While these distant worlds have only been visited by one spacecraft, Voyager 2, the Hubble Space telescope has allowed us to observe changes on these planets, including a recent change on Neptune, since Voyager 2’s visits in the late 1980’s.
Take a tour of the night sky and learn more about these two outer planets during Clark Planetarium’s Night Vision. Night Vision: Uranus & Neptune is presented by Robert Bigelow on Thursday, August 4th, in the Hansen Dome Theater at 6:45pm. Tickets available online or at the Clark Planetarium ticket desk. Free for members and $2 for everyone else.