Until five years ago, it was believed that the objects well past Neptune would be frozen wastelands.
The planet Pluto averages 30% farther from the sun than Neptune, bringing its expected surface temperature to minus 369 degrees. In July 2015, NASA’s New Horizon space probe flew by Pluto and its big moon Charon, at a distance of about 10,000 miles, discovering signs of interior heating and dark areas.
Pluto had ridges, mountains and colored plains, while Charon had a surface with deep chasms and craters. It’s believed that the dark Pluto plain named Tombaugh Regio, shaped like a heart, is a layer of nitrogen that turns to gas during the day and then freezes at night. (Pluto rotates every 6.4 days.) Pluto’s moon Charon, over half as big as Pluto has chasms comparable to our Grand Canyon.
On Jan. 1, 2019, New Horizon flew by Arrokoth, a trans-Neptunian object that was 21 miles across, made up of a larger sphere and smaller sphere joined at the ends. This encounter was at distance of about 85,000 miles. The New Horizon space probe has nearly exhausted its fuel, so it may not be able to change course and fly close by another distant body.
The objects beyond Neptune are part of the Kuiper Belt that range from 30 to 50 times the Earth-sun distance. They are discovered by a Blink comparator where two images of the same part of the sky are viewed consecutively. The trans-Newtonian objects (beyond Neptune) will appear to flash back and forth between the two images. (This same method was used to find Pluto using two images from Jan. 23 and Jan. 29 in 1930.)
The credit of finding the first trans-Neptunian object goes to David Jewitt and Jane Luu, using a large two-meter-wide reflecting telescope at the summit of Mauna Kea volcano in Hawaii in Aug. 30, 1992, after six years of searching. This object was named 1992 QB1. By the beginning of 2009, more than 1,200 trans-Neptunian objects had been found. Because of their faintness (1/10,000 of Pluto), 20% of these objects have been lost. This requires repeated searches of these objects over a two-year period to determine their orbits.
A number of these objects have a 3:2 resonance with Neptune, orbiting the sun twice for every three revolutions of Neptune. These objects are called “Plutinos,” having the same 3:2 resonance as Pluto.
Another region of these distant icy objects is in the Oort Cloud, which extends from 100 A.U. to as far as 100,000 A.U. (about half way to the nearest star).
Here is a list of the largest distant trans-Neptunian objects:
• Eris (goddess of discord in Greek mythology), 2,400 kilometers across (bigger than Pluto), orbital period = 560 years.
• Makemake (Easter Island creator), 1,500 km across, orbital period = 306 years.
• Haumea (Hawaiian matron goddess), (shaped like a football, 2,000 km at its widest), orbits sun in 283 years.
• Quaoar (Amerindian creator god), 1,260 km across, orbits sun in 287 years.
• Sedna (Intuit sea goddess), approximately 1,500 km across, orbits sun in 11,214 years, farthest trans-Neptunian body.
• Varuna (divinity of Hindu Pantheon) (1,000 km at its widest), orbits sun in 280 years.
I am making available my 2021 Night Sky Highlights (two-page document) with information on sun’s position among the stars, the evenings when the moon is seen, evening times of the year when the bright planets are seen, the evenings when the moon lines up with the bright planets, and the Sunday times of sunrise and sunset for Cumberland and surrounding communities. Request your free copy from firstname.lastname@example.org. (email copy only).
Sky sights in days ahead
Dawn begins about 6:10 a.m., sunrise about 7:11 a.m., mid day at 12:02 p.m., sunset at 4:54 p.m., dusk ends at 5:55 p.m. with 9 hours and 43 minutes of sunlight. Both Jupiter and Saturn are in the Southwest at dusk, Mars is in the eastern evening sky, Venus is in the eastern dawn. The moon is near Mars on Nov. 25.
Bob Doyle is a retired science teacher at Frostburg State University.