Close Encounter With Asteroid 2018 UA


On the morning of October 19, 2018 astronomers at the Catalina Sky Survey in Arizona detected and named asteroid 2018 UA. A short time later, traveling at 50,760 Km/hour 2018 UA passed at a distance of 7,300 – 15,350 kilometers. For perspective, television satellites orbit at more than 35,000 kilometers. 2018 UA became the 4th closest asteroid approach in recorded history.

Earth was never in danger, at 3-6 meters in diameter 2018 UA would disintegrate on contact with our atmosphere. At worst a meteoric fireball visible in the light of day might herald 2018 UA’s fiery demise. As it was, 90 minutes separated 2018 UA from initial discovery to near earth cosmic footnote. 90 minutes is worth pondering.

Asteroids are sneaky, cosmic debris ricochets at will. Without prediction, apology or reason, asteroids can appear with very little warning.

In 1998 NASA established NEO, the Near Earth Objects Observation program, administered by JPL ( NASA Jet Propulsion Laboratory).  In 2016 NASA launched PDCO ( Planetary Defense Coordination Office ), consequently NEO inherited the moniker CNEOS, (Center For Near Earth Object Studies ) .From NASA Jet Propulsion Laboratory –

The first and most important step in assessing the impact risk of an asteroid or comet is to determine whether any given object’s orbit will cross Earth’s orbit — and then how close it will actually get to our planet. JPL was determining high-precision orbits for a few NEOs even before NASA launched its NEO Observations Program, and has since upgraded its orbit models to provide the most accurate assessment available for asteroid positions and orbits.

Observatories around the world take digital images of the sky to detect moving points of light (the asteroid or comet) over days, weeks, months (and even decades!), and then report the positions of these moving objects relative to the static background of stars to the Minor Planet Center. See “How a Speck of Light Becomes an Asteroid”.The CNEOS scientists then use all this observation data to more precisely calculate an NEO’s orbit and predict its motion forward in time for many years, looking for close approaches and potential impacts to the Earth, its Moon, and other planets.

A CNEOS system called “Sentry” searches ahead for all potential future Earth impact possibilities over the next hundred years — for every known NEO. Sentry’s impact monitoring runs continually using the latest CNEOS generated orbit models, and the results are stored online.In most cases so far, the probabilities of any potential impacts are extremely small, and in other cases, the objects themselves are so small — less than 20 meters in size, or nearly 66 feet — that they would almost certainly disintegrate even if they did enter Earth’s atmosphere.

“If Sentry finds potential impacts for an object, we add it to our online ‘impact risk’ table, and asteroid observers can then prioritize that object for further observation,” said Steve Chesley of JPL, a member of the CNEOS team who was the main developer of the Sentry system. “The more measurements made of the object’s position over time, the better we can predict its future path.”

“In most cases, the new measurements mean the object can be removed from the risk list because the uncertainties in the orbital path are reduced and the possibility of impact is ruled out,” Chesley said.

More recently, CNEOS also developed a system called Scout to provide more immediate and automatic trajectory analyses for the most recently discovered objects, even before independent observatories confirm their discovery. Operating around the clock, the Scout system not only notifies observers of the highest priority objects to observe at any given time, it also immediately alerts the Planetary Defense Coordination Office of any possible imminent impacts within the next few hours or days.A recent example is the Scout-predicted impact of the small asteroid 2018 LA over Botswana, Africa.

https://www.jpl.nasa.gov/news/news.php?feature=7194

https://earthsky.org/space/small-asteroid-passed-closer-than-tv-satellites-Oct2018?utm_source=EarthSky+News&utm_campaign=e37517fdb3-EMAIL_CAMPAIGN_2018_02_02_COPY_01&utm_medium=email&utm_term=0_c643945d79-e37517fdb3-393970565

Image result for asteroid 2018 ua

In the span of 90 minutes 2018 UA went from discovery to fourth closest asteroid approach in recorded history.

Sneaky 2018 RC


Asteroids make no apology for sneakiness. February 2013, Chelyabinsk Russia, a unknown 20 meter wide meteor traveling at 18 km/second began to tear apart at an altitude of 35 kilometers. Beneath the meteor’s path shock waves knocked people off their feet. In the city of Chelyabinsk windows in over 3,600 building shattered. Over 1,200 people treated for injuries, a fireball 30 times brighter than the sun arriving without warning. A swath of destruction unleashed by a rogue 20 meter space rock.

https://en.wikipedia.org/wiki/Chelyabinsk_meteor

Five days ago the ATLAS sky survey in Hawaii discovered 2018 RC, a near earth asteroid estimated at 32-71 meters. Later today 2018 RC will come within 220,000 km, roughly half the distance between earth and the moon. As potentially hazardous asteroids go that’s freaking close. There’s no chance 2018 RC will hit earth. That said, asteroids are sneaky.For all the eyes cast at all the skies astronomers detected 2018 RC 5 days ago, Chelyabinsk came without warning.

The Virtual Telescope Project invites us to ponder2018 RC live.

Near-Earth asteroid 2018 RC: poster of the event

https://www.virtualtelescope.eu/webtv/

At 6 pm eastern daylight time the Virtual Telescope Project invites everyone to watch live images of 2018 RC. To participate click on the link above.

Earth Has An Asteroid Buddy


In 2016 planetary astronomers at the University of Arizona Lunar and Planetary Laboratory discovered a small ( 100 meter ) object moving with Earth around the Sun. Dubbed 2016 OR3, initial science speculation wondered if it might be a piece of space junk, perhaps a rogue rocket booster caught in wobbly orbit occasionally intersecting Earth orbit.

Last week at the annual Division For Planetary Sciences  meeting in Provo, Utah Vishnu Reddy from University of Arizona laid speculation to rest, identifying 2016 OR3 as an asteroid, stating in part –

“2016 HO3 is a small near-Earth object (NEO) measuring no more than 100 meters (330 feet) across that, while orbiting the sun, also appears to circle around the Earth as a quasi-satellite. Only five quasi-satellites have been discovered so far, but 2016 HO3 is the most stable of them. The provenance of this object is unknown. On timescales of a few centuries, 2016 HO3 remains within 38 to 100 lunar-distances from us.”

“One way to visualize HO3’s orbit is by picturing a hula hoop dancer — the sun in this analogy — twirling two hoops around the hips at the same time, ever so slightly out of sync. While it orbits the sun, the object makes yearly loops around the Earth.

As a result, the object appears to orbit the Earth, but it is not gravitationally bound to our planet.”

2016 HO3 is seen at the top left corner of this animation made of ten 2mn long exposures in I band using MODS1 on the left side of LBT – The telescope is tracking the moving asteroid, so background stars (and even a couple of galaxies) are trailed. Image via LBTO.

Asteroid 2016 OR3 is hardly a harbinger of doom – orbiting politely at 38 – 100 lunar distance from Earth, it is a cosmic companion which now bears official designation of quasi-satellite. NASA Jet Propulsion Laboratory said –

The asteroid’s orbit also undergoes a slow, back-and-forth twist over multiple decades. “The asteroid’s loops around Earth drift a little ahead or behind from year to year, but when they drift too far forward or backward, Earth’s gravity is just strong enough to reverse the drift and hold onto the asteroid so that it never wanders farther away than about 100 times the distance of the moon,” said Chodas. “The same effect also prevents the asteroid from approaching much closer than about 38 times the distance of the moon. In effect, this small asteroid is caught in a little dance with Earth.”

https://www.jpl.nasa.gov/news/news.php?feature=6537

“Caught in a little dance with Earth” makes me smile. Not for knowing Earth has an asteroid buddy, but for affirmation everything in our universe is caught in a little dance.

2014 JO25


On April 19, 2017 the orbit of 1 km wide asteroid 2014 JO25 will pass 4.6 LD ( 1,768,239 km ) from Earth. In astronomical terms anything within 100 LD is considered a PHA (Potentially Hazardous Asteroid ) 1 LD = distance from Earth to the Moon ( 384,400 km ). Stacked against vastness of the cosmos, 4.6 LD miss by a behemoth projectile amounts to humanity winning the lottery.

2014 JO25 will pass without consequence, no harm no foul. From NASA –

“There are no known future encounters by 2014 JO25 as close as the one in 2017 through 2500. It will be among the strongest asteroid radar targets of the year. The 2017 flyby is the closest by an asteroid at least this large since the encounter by 4179 Toutatis at four lunar distances in September 2004. The next known flyby by an object with a comparable or larger diameter will occur when 800-m-diameter asteroid 1999 AN10 approaches within one lunar distance in August 2027.”

From Earthsky –

“For backyard observers, the exciting news is that asteroid 2014 JO25 might be be visible moving across the stars though 8″-diameter and bigger telescopes. Can it be seen with smaller telescopes? Maybe, but in order to be able to detect its motion across the stars, at least an 8″ scope will be required. The asteroid will not be visible to the unaided eye, as it may show a brightness or magnitude between 10 and 11.

The asteroid is currently located in the direction of the sun, but – during the first hours of April 19 – the space rock will come into view for telescopes as it crosses the constellation of Draco. Then, during the night of April 19, asteroid 2014 JO25 will seem to move across the skies covering the distance equivalent to the moon’s diameter in about 18 minutes.

The asteroid will be close to star 41 Comae, which is very close to Beta Comae. This star is magnitude 4 and thus visible to the unaided eye. Illustration by Eddie Irizarry using Stellarium.

That’s fast enough for its motion to be detected though an amateur telescope. The best strategy to catch the space rock in your telescope is to observe a star known to be in the asteroid’s path, and wait for it.

If you are looking at the correct time and direction, the asteroid will appear as a very slowly moving “star.” Although its distance from us will make the space rock appear to move slowly, it is in fact traveling though space at a speed of 75,072 mph (120,816 km/h)!

Because it will appear to move very slowly, observers should take a good look at a reference star for a few minutes (not seconds) to detect the moving object.

Although asteroid 2014 JO25 will be closest to Earth on the morning of Wednesday, April 19, 2017, (around 7:24 a.m. Central Time / 12:24 UTC) the space rock may look a bit brighter (but still only visible in telescopes) during the night of April 19, because the asteroid will be at a higher elevation in our skies.”

http://earthsky.org/astronomy-essentials/large-asteroid-2014-jo25-close-april-19-2017-how-to-see?utm_source=EarthSky+News&utm_campaign=f53b69e38c-EarthSky_News&utm_medium=email&utm_term=0_c643945d79-f53b69e38c-393970565&mc_cid=f53b69e38c&mc_eid=a5b828713b

Today in Space


I haven’t done a space report for a while. Today we dodged a big one. A massive eruption on the far side of the sun could have had some interesting consequences had it been directed at earth.

The solar wind is steady at 396 Km/sec. A mind boggling speed when you stop to think about it, yet just an average day on the sun.

Of the current 1353 Potentially Hazardous Asteroids (PHA) – any object 100 Lunar Distance (LD) or less from earth, (LD is the distance from earth to the moon), the closest one for the remainder of 2012 passes by tomorrow. Named 2012VS76 it will come within 2.4 LD and measures 18m across. The largest is 4179 Toutatis, on Dec. 12 it will pass 18 LD. for which we can all be thankful as Toutatis is nearly 3 Km. wide.

Sunspots AR1610 and 1614 are getting restless, NASA predicts only a 25% chance of an M class eruption and 5% for an X. There has been some impressive geomagnetic activity lately. Geomagnetic storms occur in the upper atmosphere when magnetic energy from the sun, propelled by solar wind or energy from coronal holes messes with our magnetosphere. A recent magnetic storm resulted in rare red auroras. We can expect spectacular auroras for the next few days.

http://spaceweather.com

First photo – NASA – recent magnetic eruption. Followed by a picture of red auroras taken by David E. Carter near Whitehorse, NWT