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.”

“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.”

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.

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