My Catalina Sky Survey teammate Greg Leonard was asteroid hunting with our 60 inch telescope on Mt. Lemmon, Arizona when he came across an unknown moving point of light in the night sky. After Greg reported his observations to the Minor Planet Center his discovery was tracked by telescopes in California, Romania, Germany, New Mexico, Arizona, Bavaria, and Japan. Astronomers used these data to calculate that Greg’s discovery orbits the sun between Venus and Earth , estimate its size to be approximately twice the length of a football field, and give it the name 2026 BX4. NASA classifies it to be a Potentially Hazardous Asteroid, however, since it doesn’t cross the Earth’s orbit it is not an immediate impact threat. In fact it will not come as close to us as it can on its current path until February 17, 2075 when it will pass less than 6 times the moon’s distance from us. Because 2026 BX4’s orbit is entirely within the Earth’s path about the Sun it is classified to be an Atira asteroid. These space rocks are difficult to discover and track because they are always near the Sun in the sky. 2026 BX4 could become an impact threat by gravitational interactions with Earth, Venus or another asteroid. There are also Aten asteroids which spend most of their time inside the Earth’s orbit but cross it and are more of a threat than an Atira asteroid like 2026 BX4. Currently the most dangerous Aten asteroid is Apophis which will safely pass closer to us than the communication satellites on Friday February 13, 2029. Asteroid hunters will continue to discover and track both Atira and Aten asteroids to make sure none of them sneak up on our home planet from the direction of the Sun.

Recently my Catalina Sky Survey teammates Carson Fuls and Greg Lenoard discovered an Aten asteroid which orbits the Sun once every 272 days and on a path that crosses the orbits of Venus and Earth a number of times each year. Atens account for only about 6% of the Earth approaching asteroids that asteroid hunters discover. They are relatively dim and difficult to discover because they spend most of their time inside the Earth's orbit with their sunlit side facing away from us. For example Carson and Greg's newly discovered asteroid, 2017 WJ16, is bright enough for asteroid hunters to track for only about 50 nights every couple of years. It is about 150 feet in diameter and travels on an orbit which can bring it to a bit more than three times the Moon's distance from Earth. When 2017 WJ16 is closer to the Sun than Earth it travels faster then we do allowing it to catch and just barely cross our orbit as we both travel about the Sun. In 2020, 2017 WJ16 will make one of it's closer approaches to us when it comes to about less than 5 times the Moon's distance from our home planet. At that time it will be traveling at 2.9 miles/second relative to us which is well within reach of our current rocket technology. I suspect that in the future if the pattern of colors which 2017 WJ16 reflects, reveals a high metal or water content humans will mine it to construct and operate their colonies in space.

According to NASA an average of one catalogued piece of space junk per day has come down to Earth over the past 50 years. Research is described which can track space junk in the atmosphere and provide the starting location and altitude for tracking clouds of environmentally problematic toxic chemical and/or nuclear contaminants released by the disintegration of reentering spacecraft.

The NASA Curiosity Rover has shown us evidence of ancient rivers and bodies of liquid water on the martian surface. Given it's thin cold atmosphere, seeps of liquid water, presently on the surface of Mars which are capable of hosting microbial life appear to be unlikely. Scientists were thus surprised when high resolution imaging of the red planet's surface revealed thousands of intriguing dark streaks called RSL on hundreds of rocky slope areas. These fascinating features slowly extend down hill and grow during the martian warm season, fade during the colder season, and reappear during the next martian warm period. On Earth features like these are produced by seeps of liquid water. However, on Mars a careful study of 151 RSL features at ten different sites using the high resolution camera on NASA's Mars Reconnaissance Orbiter reveal that they occur almost entirely on slopes which are greater than 27 degrees. This new research published in Nature Geoscience suggests that RSL are composed of solid particles in dry granular flows which unlike water seeps appear to end on many of the dunes when it's slope falls below a critical value. What makes RSL tick remains a mystery and likely involves small amounts of water trapped from the atmosphere. Currently surface conditions are hostile to life as we know it, however, the possibility of finding evidence of ancient life or perhaps even still existing microbe colonies in deep sub surface pockets of water are reasons to continue to explore our next door neighbor without contaminating it.

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.

Astronomers continue to be delighted when they discover an Earth sized planet. Scientists were thus very disappointed when the red dwarf star hosting the nearest such planet, Proxima b some 4.2 light years away, turns out to have the nasty habit of emitting bursts of radiation which are likely to sterilize and/or remove the atmospheres of it's family of planets. Recently, hope of finding a nearby Earth was rekindled when scientists at the European Southern observatory in Chile discovered a small planet circling what appears to be a quiet well behaved red dwarf star 11 light years from us. Astronomers are not yet sure that this newly discovered Earth sized planet lies within it's stars habitable zone where liquid water could exist on it's surface. Jumping the gun, ET enthusiasts have beamed a friendly message in the direction of another nearby red dwarf planet system. Their target the super Earth planet, GJ 273b is located some 12.4 light years away near the bright star Sirius in the constellation of Canis Major. At this distance a civilization on GJ 273b could have already received a picture of humanity by deciphering 'I love Lucy' and other TV signals it has been picking up for 50 years or so. The next generation of very large telescopes will allow astronomers to search for the presence of oxygen and other molecules which indicate the presence of life in the atmospheres of nearby worlds. In the mean time we have more reasons to be thankful for what we have here on planet Earth. For Travelers in the Night this is Dr. Al Grauer. Go to travelersinthenight.org program 417 for more information.