This article was contributed by David Baumgartner as part of a local series on astronomy. Lea este articulo en español aqui.
Two of the most unknown planets in our solar system are the two large gas giants- Uranus and Neptune. They are very large in size but so far in distance that it’s hard to view from this amateur astronomer’s back yard. Each has a greenish tint to them, making it somewhat easer to distinguish from the stars. But each can be viewed with binoculars if one knows where to look.
On the night of March 13th, 1781 William Herschel made history when he accidentally stumbled upon a round bluish-green object in the constellation Gemini. At first he mistakenly thought that he had discovered another comet, for it was moving slowly across the sky not unlike a comet would do. Upon further analysis Herschel realized that he had indeed discovered a planet beyond Saturn. The planet later on came to be known as Uranus, which just happens to be, in mythology terms, the father of Saturn.
Today we know that Uranus is the third largest planet in our solar system, behind Jupiter and Saturn. Uranus measures some 32,000 miles across, compared to Earth’s 8,000 miles. Uranus is over 19 times farther away from the sun than the Earth. The sun’s light takes some 8.5 minutes to get to the Earth from. The light from the sun takes around 2.6 hours to reach the gassy planet.
By the end of the 18th century astronomers where becoming confused with the orbit of Uranus. Uranus was the only planet that did not obey the planetary rules, as we knew them. The astronomers had figured that some object beyond Uranus was causing the unusual path of this planet. And then on the night of September 23, 1846 at the Berlin Observatory, Johann Gottfried Galle discovered Neptune. Now this just baffles my mind, how they were able to figure all this out. Remember they didn’t have the equipment and expertise we have at our fingertips today.
Just imagine; its 1846, you’re looking at this small greenish looking Uranus through your crude telescope of the time, and somehow you figure out that it has an odd shape orbit compared to the rest of the planets. With that, and other information you have on hand, you figure out there must be another object or planet beyond Uranus that is causing the disfiguration of its orbit. You know this mystery object is out there, but where?
It is right in front of you. The best thing here is that you get to name it. So they are all set now; Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Baumgartner, named for evermore. But wait; along comes Clyde Tombaugh in 1930 and discovers the planet Pluto. So always be ready for change. As long as they keep on building bigger and better telescopes you can be sure that more will be added to our list. Now whether they call them planets or not is yet to be seen.
What we knew of Neptune was somewhat limited at that time. But things changed in August of 1989 when Voyager 2 flew by Neptune to reveal the unknown. We now know that Neptune’s atmosphere is a colorful turquoise. Voyager’s camera revealed a dark Earth size spot similar to the Great Red Spot on Jupiter. It also revealed there were thin irregular rings around the planet, a smaller version of Saturn’s, as well as six new moons to add to Triton and Nereid. Neptune is somewhat more than 30,000 miles across in diameter and more than 30 times farther away from the sun than Earth. By the way; Voyager I and II are still on their way leaving our solar system. Amazing!
Right now you can find Uranus and Neptune in the constellations Aries and Pisces, respectively. You can find the actual location of each in any one of the many astronomy magazines, such as “Astronomy” and “Sky and Telescope.” Of course, if you have a go-to equipped telescope, which I am fortunate to have, your scope will take you right to it. It is almost like cheating. Many of the old timers feel if you can’t navigate around the heaven on your own, you are not doing yourself or the craft justice. I must admit that I do enjoy the star-hoping method from time to time; it certainly is more of a challenge. But the main goal here is to find your object. Who really cares how you get there? Clear skies.
What’s up at night this month?
Nov. 9: Moon passes 1.0° north of Venus
Nov. 13 New Moon
Nov. 14: Moon passes 0.9° north of Antares
Nov. 16: Mercury passes 3° north of Antares
Nov. 17: Leonid meteor shower peaks
Nov. 20: First Quarter Moon
Nov. 20: Moon passes 3° south of Saturn
Nov. 21: Moon is at perigee (9229,795 miles from Earth)
Nov. 22: Moon passes 1.5° south of Neptune
Nov. 25: Moon passes 3° north of Jupiter
Nov. 26 Moon passes 3° north of Uranus
Nov. 27 Full MoonNov 28 Venus passes 4° north of Spica