Travelers In The Night

On a recent night my Catalina Sky Survey teammate Vivian Carvajal found 4 Earth approaching space rocks with our small but mighty Schmidt telescope on Mt. Bigelow, Arizona. These Earth approaching asteroids are all small with an average diameter about the width of tennis court. On their current paths none of them come closer than about 4 lunar distances from our home planet.

In 2012 as it crossed the orbit of Neptune heading towards the Sun a small space rock was 250 times fainter than can be detected by the Hubble Space Telescope. Five years later, after it had rounded the Sun, it became visible in asteroid hunter's telescopes for about 16 days, as it streaked across our planet's orbit at 37 miles per second, as it continued to move away from the Sun. During that brief period of time it was discovered by the PanSTARRS group in Hawaii, tracked by telescopes around the world, and given the name Oumuamua (“Oh-moo-ah-moo-ah”). Turns out that previous to the discovery observations, sightings too sparse to report, were obtained by my team using the Catalina Sky Survey's Schmidt telescope on Mt. Bigelow, Arizona. In 2024 this unusual space rock will cross Pluto's average distance from the Sun traveling on a path which will take it into deep interstellar space. Since we don't know how Oumuamua could obtained it's current trajectory from processes in our solar system, it is safe to presume that it originated in truly deep space. The mystery of Oumuamua deepened when astronomers measured it's brightness to change regularly by nearly 10 times over a 7.3 hour period of time. If these brightness variations are due to it's shape, and thus the amount of sun light reflected as it rotates, Oumuamua looks like a cigar. Even though Elon Musk's SpaceX Mars rocket could catch Oumuamua, it is more cost effective is to simply wait to discover another one of the several interstellar asteroids which pass by us each year.

Artificial light at night also known as light pollution is degrading human safety and health as well as damaging the natural environment on which we all depend. The loss of the connection with the natural night sky has happened over the past 100 years. Restoring the natural night sky is relatively simple and can even save money. Before restoration can effectively begin it is essential to make night sky brightness measurements in both natural night sky and urban locations.

Recently there were four fireball meteors, brighter than the planet Venus, which exploded over Germany, France, Ohio, and Arizona within the space of only 10 hours. A total of 1320 individuals were treated to light shows and reported their observations to the American Meteor Society. The one which exploded over Arizona was probably several feet in diameter and entered the Earth's atmosphere over Flagstaff. This event was observed in Arizona, California, Nevada, Utah, New Mexico, and Colorado. It was recorded by numerous electronic security and dashboard cameras and was visible for from 3 to 7 seconds. This meteor also produced a booming sound which was reported by about a dozen different observers. The fireball was last seen over Happy Jack, Arizona and is likely to have produced meteorite fragments which are scattered along Interstate 17 somewhere in the rugged country between Phoenix and Flagstaff. There are likely to be on the order of 1,000 fireball events over the Earth every day. Most of them occur over the oceans or during the day and pass unobserved by humans. During the first 10 months of 2017 the most energetic fireball event occurred when a meteoroid entered the Earth's atmosphere at 8.5 miles/second above the ocean between Australia and Antartica. If you record a fireball with your dash cam or security camera report it to the American Meteor Society. Your data will be very important in finding out where it came from in the solar system as well as to indicate where it might be possible to find pieces of it on the ground.

Humans can mitigate the damage done by the impact of an asteroid given a sufficient lead time. In 1998, the US Congress mandated NASA to detect and track 90% of the 1 km sized asteroids capable of effecting local mass destruction as well as global disruption of agriculture and other human activities. This goal has been accomplished. In 2005 Congress extended the mandate to require NASA to detect and track 90% of the 140-m asteroids capable of destroying a large metropolitan area.