Show Notes
Asteroids appear as moving points of light in an asteroid hunter's images so that when my Catalina Sky Survey teammate Alex Gibbs spotted a fuzzy moving object he immediately suspected it to be a comet. The data obtained by astronomers over the next 8 days enabled scientists at the Minor Planet Center to verify Alex's 31st comet discovery and give it the name C/2018 A6 (Gibbs). In January of 2018 it was in the constellation of Leo traveling from the vast empty space above the Sun's north pole toward the plane of the solar system which contains all of the planets and most of the asteroids. In March of 2018 Comet C/2018 A6 (Gibbs) will cross the plane of the solar system a bit farther from the Sun than the giant planet Jupiter's orbit. After that it will continue on a wide arcing parabolic path, pass under the Sun's south pole in the summer of 2019, and once again cross the plane of the solar system in February of 2021. After that it will continue into the vast empty space above the Sun's north pole from whence it came. How a comet brightens as it approaches the Sun is difficult to predict. With luck humans will be able to spot Comet C/2018 A6 (Gibbs) with their naked eye, binoculars, or a small telescope as it pays a rare visit to our planet's neighborhood.
More from Travelers In The Night
My Catalina Sky Survey teammate Greg Leonard's discovery of, 2018 FO5, a three football field diameter asteroid that can come closer than our Moon is a reminder that we need to keep searching for the many thousands of Potentially Hazardous asteroids larger than 500 feet in diameter which are likely to exist.
After completing a sample and return mission to the asteroid Ryugu (ree-oo-goo) and a fly by of asteroid Torifune (toh-ree-foo-neh), the Japanese asteroid exploring spacecraft Hayabusa2 (high-yah-BOO-sah-too )is on its way to fly by the rapidly spinning tiny asteroid 1998 KY2 .
My Catalina Sky Survey teammate Jess Johnson was very surprised when the large comet with a long stringy tail, which he has just imaged with our 60 inch telescope on Mt. Lemmon, Arizona, was an unknown object. Jess quickly emailed his discovery observations along with a description of the comet's coma and tail to the Minor Planet Center. Over the next eight days astronomers at 11 different observatories around the world tracked Jess's new comet. Scientists at the Minor Planet used these data to calculate it's path around the Sun, verify it to be a comet, and give it the name C/2018 F3 (Johnson). We now know that Comet C/2018 F3 (Johnson) had crossed the orbit of Pluto in 1997 and had reached it's closest point to the Sun 217 days previous to Jess's discovery observations. Further, about two weeks before Jess spotted it , moving through the constellation of Leo, Comet 2018 F3 (Johnson) had streaked unnoticed past the Earth. Unfortunately Jess's comet is likely to be visible only in electronic camera images and in 2037 will once again cross Pluto's average distance from the Sun on a path which will take it into truly deep space. Until a few years ago all of the comets human astronomers had observed originated in the distant regions of our solar system, the Kuiper Belt or the Oort Cloud . Perhaps C/2018 F3 (Johnson) is an interstellar visiting Comet and is thus a sample of a place currently beyond our reach.
Viewed in a telescope an asteroid appears as a moving star like point of light while a comet often appears to be a fuzzy point of light with a tail. The orbit of an asteroid is governed force of gravity exerted by the Sun, planets, and in some cases our moon. In addition the Yarkovsky Effect can cause the orbit of a spinning asteroid to shift slightly over millions of years as the heat it absorbs from the Sun radiates back into space. Comets on the other hand can have orbits which change erratically as its nucleus emits small rocket like bursts when frozen gases trapped within it are heated by the Sun.
On Saint Patrick's Day, while searching for Earth approaching asteroids with the Catalina Sky Survey's 60 inch telescope on Mt. Lemmon, Arizona I spotted a slightly enlarged star like object with a tiny tail moving through the constellation of Virgo. After checking to see that it was not a known comet, I sent my discovery observations along with a description of it's coma and tail to the Minor Planet Center. Turns out that it had been observed as a moving point of light, but not noticed to be a comet, by the PanSTARRS group in Hawaii 3 month's earlier. Given the PanSTARRS historical observations along with those from other observatories around the world it only took scientists at the Minor Planet Center 2 days of additional observations to verify it to be a newly discovered comet. Since the naming rules state that a comet should be named after the first observer that identified it to be a comet it was given the C/2018 F1 (Grauer). In December of 2018 and July of 2019 Comet C/2018 F1 (Grauer), which I share with my wife Annie Grauer, will be closest to Earth on it's 5,555 year orbital path about our Sun. Unfortunately it is not likely to be visible to the unaided eye, appearing only as faint moving comet in the night sky on electronic camera images, leaving us to speculate on the condition of humanity when Comet C/2018 F1 (Grauer) returns in the year 7573 AD.