Travelers In The Night

On December 25, 2017, while searching for Earth approaching asteroids in the constellation of Virgo, the Universe gave my Catalina Sky Survey teammate Greg Leonard a Christmas present in the form of a comet which now bears his name. Comet P/2017 Y3 (Leonard) orbits the Sun once every 31 years on a highly elliptical path which takes it from between the orbits of Earth and Mars out to almost the planet Uranus's average distance from the Sun. Since it has been observed for only a very short piece of it's path about the Sun, it is not possible to accurately predict Comet Leonard's location very far into the future. In 2017 and 2018 it appeared as a faint fuzzy point of light in the night sky and never came came closer than about 150 million miles from Earth. Comet Leonard's next visit to our neighborhood will be in 2033 or 2034. At some point in the future it's orbit could bring much closer to Earth as it comes into the inner solar system about twice every human lifetime. Greg's comet is classified as a Halley family comet and although it is difficult to predict how a comet will brighten as it approaches the Sun, it is unlikely that it will ever become as bright as it's famous cousin. That situation could change when Comet Leonard comes near the giant planet Jupiter. In the past Jupiter has sent Comets in our direction or ejected them from the solar system. Only time will tell.
For Travelers in the Night this is Dr. Al Grauer.

The visually stunning Lunar Crater Pierazzo, named for the late Planetary Scientist Elizabeth “Betty” Pierazzo was observed by the Artemis II Crew as they passed over the Moon’s far side.  It is a 5.9 mile diameter crater with white streaks or rays which extend more than 50 miles in all directions.

Most asteroids are located in the lonely space between Mars and Jupiter where the average distance between two asteroids is about 600,000 miles. Even though there is a tremendous space between asteroids they occasionally collide and pieces of them become Earth approaching objects. Most of them remain close to the plane of the solar system, however, a few are sent on paths which take them into the extremely lonely space high above and far below the orbits of the planets about the Sun. In 2017, my team, the Catalina Sky Survey, discovered 13 of these loneliest asteroids whose paths are tilted more than 45 degrees to the plane of the solar system. They have an average diameter about 4 times larger than that of the 987 asteroids we discovered in 2017. Even though 13 is a small sample it is interesting to speculate what this size difference could mean. In 2013, astronomers used the Subaru Telescope on Mauna Kea in Hawaii to discover that main belt asteroids with orbits which are highly inclined to the plane of the solar system tend to be larger and made of stronger materials than those asteroids which reside in the plane of the solar system. They attribute these differences to the collisions which must have occurred to send asteroids into highly inclined orbits about the Sun. If this result applies to the lonely near Earth asteroids we discovered then perhaps they are made of very strong materials and could be of particular interest to asteroid miners.

My Catalina Sky Survey teammate Josh Hogan has discovered a 2 football field diameter asteroid that was placed on NASA’s Sentry list because it has a tiny minuscule but non-zero chance of impacting our home planet. With this motivation my team the Catalina Sky Survey, the Pan STARRS group in Hawaii,  the ATLAS group with telescopes Hawaii, Chile, and South Africa , the Vera C. Rubin telescope in Chile, will be soon joined NASA’s NEO Surveyor and groups world wide in a planet wide defense network.

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.