Spot the First Planet Ever Discovered

The sky this month (and next) offers an opportunity to see the first planet to be “discovered” in our solar system—Uranus! At magnitude 5.7 it can be spotted with the unaided eye under very dark viewing conditions. The smallest pair of binoculars will definitely show it, while telescopes will reveal that it is indeed a planet and not a star.


The five naked-eye planets—Mercury, Venus, Mars, Jupiter and Saturn—have all been known since antiquity. It never occurred to anyone that there might be more planets out beyond Saturn. It was left to the “amateur astronomer” Sir William Herschel to accidentally discover Uranus on the night of March 13, 1781, while sweeping the sky from England with his homemade 6.2-inch reflecting telescope.

To discover Uranus for yourself, begin by setting your Scientifics’ Star and Planet Locator to about 9 p.m. in November. On a dark (i.e., no bright Moon in the sky) evening facing south, locate the huge “Great Square” of Pegasus asterism (which we’ve discussed in past Sky Talk installments). Beneath it, and stretching to its lower left and then northward in the sky, is the rather dim sprawling constellation of Pisces. Note the point where the two lines of stars meet—and then the star just above it to the north. That’s your anchor point for locating Uranus. (Yes—some care and patience is needed in finding the planet for the very first time, but it’s well worth the effort.)

Point your glasses at this star and then scan to the right a binocular field or so until you see a greenish-looking object. You’ve just found the planet Uranus! Aside from its characteristic hue, you can tell it’s not a star since it doesn’t twinkle (planets don’t since they have sizeable disks while stars are essentially pinpoints). Even a small telescope at magnifications of 50X and above will show Uranus’ little greenish disk. Imagine Sir William’s excitement at unexpectedly seeing it for the very first time!

In closing this month’s installment, mention should be made that the Moon will once again occult the bright star Aldebaran on the evening of Nov 5th at sometime around 8 p.m. EST for those in the eastern part of the country. See the March Sky Talk for more complete information on observing these events. As mentioned there, the exact time of disappearance depends on both longitude and latitude. It’s best to look at the Moon and star well before any predicted times. Then watch our satellite slowly creep up to Aldebaran and finally cover it, as this lovely “Queen of the Night” moves eastward in the sky. The disappearance itself is spectacular but instantaneous—like someone turning off a light switch!

— James Mullaney

Former assistant editor at Sky & Telescope magazine & author of nine books on stargazing. His latest, Celebrating the Universe!, is available from