Show Notes
My Catalina Sky Survey teammate Carson Fuls was observing, in the constellation Lynx, with our Schmidt telescope on Mt. Bigelow, Arizona , when within the space of only 35 minutes, he discovered two small space rocks well before they made very close approaches to Earth. 79 hours after Carson discovered the first, 2018 CB, this approximately 70 foot diameter space rock passed about 1/5 of the Moon's distance from us. Turns out that the second of Carson's duo, an approximately 50 foot diameter space rock got near us first, when 62 hours after Carson discovered 2018 CC, it came to less than 1/2 of the Moon's distance from the surface of planet Earth. Since we didn't have a large enough, properly equipped telescope to measure the pattern of colors each of Carson's discoveries reflects from the Sun we can only estimate their physical sizes and guess at their densities and chemical compositions. In any event, if either of these space rocks were to strike the Earth they would likely explode at an altitude about 100,000 feet above the Earth's surface, releasing the energy of tens of thousands of pounds of TNT, producing a spectacular light show. Both of Carson's discoveries could be similar to the space rock which exploded over Chelyabinsk, Russia breaking windows, injuring nearly 1,500 people, and producing numerous fragments which made it to the ground. If either of Carson's discoveries had been on an impact trajectory with Earth, asteroid hunters would have had time to warn people in the effected area to stay away from doors and windows.
More from Travelers In The Night
The Vera C. Rubin Observatory, also known as LSST, with its 8.4 m mirror, the width of a tennis court, and the worlds largest 3.2 gigapixel camera, roughly the size of a small car, will image the entire sky every 3 or 4 nights in such a way as to detect objects that change in position and/or brightness. It is estimated the LSST will discover one or two new impacting small asteroids per year and provide several days of lead time for follow up telescopes to track an impactor into the atmosphere to find meteorites whose chemical composition will tell us about where they originated.
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.