Asteroids Smack Jupiter More Often Than Astronomers Thought

Jupiter Impact
Jupiter Impact
Pow: The July 1994 impact of Comet Shoemaker-Levy 9 on Jupiter, captured by the Hubble Space Telescope. Credit: R. Evans/J. Trauger/H. Hammel/HST Comet Science Team/NASA.

Are you keeping a eye on Jupiter? The King of the Planets, Jove presents a swirling upper atmosphere full of action, a worthy object of telescopic study as it heads towards another fine opposition on May 9th, 2018.

Now, an interesting international study out of the School of Engineering in Bilbao, Spain, the Astronomical Society of France, the Meath Astronomical Group in Dublin Ireland, the Astronomical Society of Australia, and the Esteve Duran Observatory in Spain gives us a fascinating and encouraging possibly, and another reason to keep a sharp eye on old Jove: Jupiter may just get smacked with asteroids on a more regular basis than previously thought.

The study is especially interesting, as it primarily focused in on flashes chronicled by amateur imagers and observers in recent years. In particular, researchers focused on impact events witnessed on March 17th 2016 and May 26th, 2017, along with the comparison of exogenous (of cosmic origin) dust measured in the upper atmosphere. This allowed researchers to come up with an interesting estimate: Jupiter most likely gets hit by an asteroid 5-20 meters in diameter (for comparison, the Chelyabinsk bolide was an estimated 20 meters across) 10 to 65 times every year, though researchers extrapolate that a dedicated search might only nab an impact flash or scar once every 0.4 to 2.4 years or so.

Compare this impact rate with the Earth, which gets hit by a Chelyabinsk-sized 20-meter impactor about once every half century or so. Incidentally, we know this impact rate on Earth better than ever before, largely due to U.S. Department of Defense classified assets in space continually watching for nuclear tests and missile launches, which also pick up an occasional meteor “photobomb.”

Small asteroid impacts over the span of the Earth over a 20 year period. NASA/Planetary Science.

One reason we may never have witnessed a meteor impact on Jupiter is, astronomers (both professional and amateur) never thought to look for them. The big wake-up call was the impact of Comet Shoemaker-Levy 9 in July 1994, an event witnessed by the newly refurbished Hubble Space Telescope as the resulting impact scars were easily visible in backyard telescopes for weeks afterward. Back in the day, speculation was rampant in the days leading up to the impact: would the collision be visible at all? Or would gigantic Jupiter simply gobble up the tiny comet fragments with nary a belch?

Australian amateur astronomer Anthony Wesley also caught an interesting impact (scar?) in 2009, and every few years or so, we get word of an elusive flash reported on the Jovian cloudtops, sometimes corroborated by a secondary independent observation or a resulting impact scar, and sometimes not.

An impact scar (top center on the disk) on Jupiter, captured on July 19th, 2009. Image credit: Anthony Wesley.

Of course, there are factors which will lower said ideal versus the actual observed impact rate. There’s always a month or so a year, for example, when Jupiter is near solar conjunction on the far side of the Sun, and out of range for observation. Also, we only see half of the Jovian disk from our Earthly perspective at any given time, and we’re about to lose our only set of eyes in orbit around Jupiter – NASA’s Juno spacecraft – later this summer, unless there’s a last minute mission extension.

On the plus side, however, Jupiter is a fast rotator, spinning on its axis once every 9.9 hours. This also means that near opposition, you can also track Jupiter through one full rotation in a single evening.

Finding Jupiter: looking eastward tonight at around 11PM local. Credit Stellarium.

Then there’s the planet’s location in the sky: Currently, Jupiter’s crossing the southern constellation of Libra, and opposition for Jove moves about one astronomical constellation eastward along the ecliptic a year. Jupiter will bottom out along the ecliptic in late 2019, and won’t pop back up north of the celestial equator until May 2022. And while it’s not impossible for northern observers to keep tabs on Jupiter when it’s down south, we certainly get more gaps in coverage around this time.

Hale-Bopp’s close inbound passage near Jupiter in 1996. Credit: NASA/JPL-Horizons.

Should we hail Jove as a protective ‘cosmic goal-tender,’ or fear it as the bringer of death and destruction? There are theories that Jupiter may be both: for example, Jupiter altered the inbound path of Comet Hale-Bopp in 1997, shortening its orbital period from 4,200 to 2,533 years. The 2000 book Rare Earth even included the hypothesis of Jupiter as a cosmic debris sweeper as one of the factors for why life evolved on Earth… if this is true, it’s an imperfect one, as Earth does indeed still get hit as well.

All reasons to keep an eye on Jupiter in the 2018 opposition season.

-See something strange? The ALPO Jupiter observers section wants to know!

Jupiter Just Got Nailed By Something

Austrian amateur astronomer Gerrit Kernbauer recorded these brief flash of light at Jupiter's limb on March 17, 2016. It was confirmed by another amateur video observation made by John McKeon of Ireland. Credit: Gerrit Kernbauer
Austrian amateur astronomer Gerrit Kernbauer recorded these brief flash of light at Jupiter’s limb on March 17, 2016. It was confirmed by another amateur video observation made by John McKeon of Ireland. Credit: Gerrit Kernbauer

Jupiter may be the biggest planet, but it sure seems to get picked on. On March 17, amateur astronomer Gerrit Kernbauer of Mödling, Austria, a small town just south of Vienna, was filming Jupiter through his 7.8-inch (200mm) telescope. 10 days later he returned to process the videos and discovered a bright flash of light at Jupiter’s limb.


Possible asteroid or comet impact on Jupiter on March 17

“I was observing and filming Jupiter with my Skywatcher Newton 200 telescope, writes Kernbauer. “The seeing was not the best, so I hesitated to process the videos. Nevertheless, 10 days later I looked through the videos and I found this strange light spot that appeared for less than one second on the edge of the planetary disc. Thinking back to Shoemaker-Levy 9, my only explanation for this is an asteroid or comet that enters Jupiter’s high atmosphere and burned up/explode very fast.”

Comet Shoemaker-Levy 9 broke up into many fragments (upper left photo) which later slammed into Jupiter's southern hemisphere one after another to create a string of dark blotches in July 1994. Credit: NASA/ESA
Comet Shoemaker-Levy 9 broke up into many fragments (upper left photo) which later slammed into Jupiter’s southern hemisphere one after another to create a string of dark blotches in July 1994. Credit: NASA/ESA

The flash certainly looks genuine, plus we know this has happened at Jupiter before. Kernbauer mentions the first-ever confirmed reported comet impact that occurred in July 1994. Comet Shoemaker-Levy 9, shattered to pieces from strong tidal forces when it passed extremely close to the planet in 1992, returned two years later to collide with Jupiter — one fragment at a time.  21 separate fragments pelted the planet, leaving big, dark blotches in the cloud tops easily seen in small telescopes at the time.


Video of possible Jupiter impact flash by John McKeon on March 17, 2016

Not long after Kernbauer got the word out, a second video came to light taken by John McKeon from near Dublin, Ireland using his 11-inch (28 cm) telescope. And get this. Both videos were taken in the same time frame, making it likely they captured a genuine impact.

With the advent of cheap video cameras, amateurs have kept a close eye on the planet, hoping to catch sight of more impacts. Two factors make Jupiter a great place to look for asteroid / comet collisions. First, the planet’s strong gravitational influence is able to draw in more comets and asteroids than smaller planets. Second, its powerful gravity causes small objects to accelerate faster, increasing their impact energy.

According to Bad Astronomy blogger Phil Plait: “On average (and ignoring orbital velocity), an object will hit Jupiter with roughly five times the velocity it hits Earth, so the impact energy is 25 times as high.” Simply put, it doesn’t take something very big to create a big, bright bang when it slams into Jove’s atmosphere.

It wasn’t long before the next whacking. 15 years to be exact.

This impact spot, discovered in 2009 by Anthony Wesley, was also visible in amateur telescopes. Credit: NASA, ESA, and H. Hammel (Space Science Institute, Boulder, Colo.), and the Jupiter Impact Team
This impact spot, discovered in 2009 by Anthony Wesley, was also visible in amateur telescopes. Credit: NASA, ESA, and H. Hammel (Space Science Institute, Boulder, Colo.), and the Jupiter Impact Team

On July 19, 2009, Australian amateur Anthony Wesley was the first to record a brand new dark scar near Jupiter’s south pole using a low-light video camera on his telescope. Although no one saw or filmed the impact itself, there was no question that the brand new spot was evidence of the aftermath: NASA’s Infrared Telescope Facility at Mauna Kea picked up a bright spot at the location in infrared light.


Jupiter impact event recorded by Christopher Go on June 3, 2010

Once we started looking closely, the impacts kept coming. Wesley hit a second home run on June 3, 2010 with video of an impact flash, later confirmed on a second video made by Christopher Go. This was quickly followed by another flash filmed by Japanese amateur astronomer Masayuki Tachikawa on August 20, 2010.


Jupiter impact flash on August 20, 2010 by Masayuki Tachikawa

Prior to this month’s event, amateur Dan Petersen visually observed a impact flash lasting 1-2 seconds in his 12-inch (30.5 cm) scope on September 10, 2012, which was also confirmed on webcam by George Hall.

Keep ’em comin’!

Will an Asteroid Smack Jupiter in 2022?

A recent space rock discovery has sent a minor buzz through the community that tracks such objects. And as usual, it has also begun to attract the dubious attention of those less than honorable sites — we won’t dignify them with links — that like to trumpet gloom and doom, and we thought we’d set the record straight, or at very least, head the Woo off at the pass as quickly as possible.

The asteroid in question is 2014 KM4. Discovered earlier this month, this 192 metre space rock safely passed by the Earth-Moon system at 0.17 A.U.s distant on April 21st. No real biggie, as asteroids pass lots closer all the time. For example, we just had a 6-metre asteroid named 2014 KC45 pass about 48,000 miles (about 80,000 kilometres) from the Earth yesterday morning. That’s about twice the distance of the orbit of geosynchronous satellites and 20% the distance to the Moon.

Sure, it’s a dangerous universe out there… you only have to stand in the Barringer Meteor Crater in Arizona outside of Flagstaff or watch the videos of a meteor exploding over Chelyabinsk last year the day after Valentine’s Day to know that. But what makes 2014 KM4 interesting is its orbit and its potential to approach Jupiter in about seven years.

Or not. One dilemma with orbital mechanics is that the precision of a known orbital path relies on the number of observations made and that position gets more and more uncertain as we project an object’s position ahead in space and time. 2014 KM4 is on a 5.08 year orbit inclined 5.2 degrees to the ecliptic plane that brings it juuusst inside the Earth’s orbit — hence the Apollo designation — and out to an aphelion point very near Jupiter at 5.2 A.U.s from the Sun. But that’s only based on 14 observations made over a span of 5 days. The current nominal trajectory sees 2014 KM4 pass about 0.1 A.U. or 15.5 million kilometres from Jupiter on January 16th 2022. That’s inside the orbit of Jupiter’s outermost moons, but comfortably outside of the orbit of the Galilean moons. The current chance of 2014 KM4 actually impacting Jupiter sits at around 1% and the general trend for these kinds of measurements is for the probability to go down as better observations are made. This is just what happened last year when comet 2013 A1 Siding Spring was discovered to pass very close to Mars later this year on October 19th.

We caught up with JPL astronomer Amy Mainzer, Principal Investigator on the NEOWISE project currently hunting for Near Earth Asteroids for her thoughts on the subject.

“The uncertainty in this object’s orbit is huge since it only has a 5 day observational arc,” Mainzer told Universe Today. “A quick check of the JPL NEO orbit page shows that the uncertainty in its semi-major axis is a whopping 0.47 astronomical units! That’s a huge uncertainty.”

“At this point, any possibility of impact with Jupiter is highly uncertain and probably not likely to happen. But it does point out why it’s so important to extend observational arcs out so that we can extend the arc far enough out so that future observers can nab an object when it makes its next appearance.”

Jupiter takes a beating from Comet Shoemaker-Levy 9. Credit: NASA/Hubble Space Telescope team.
Jupiter takes a beating from Comet Shoemaker-Levy 9. Credit: NASA/Hubble Space Telescope team.

IF (that less than 1% “IF”) 2014 KM4 were to hit Jupiter, it would represent the most distant projection ahead in time of such an event. About two decades ago, humanity had a front row seat to the impact of comet Shoemaker-Levy 9 into Jupiter in July 1994. At an estimated 192 metres in size, 2014 KM4 is about the size of the “D” fragment that hit Jupiter on July 17th 1994. 2014 KM4 has an absolute magnitude (for asteroids, this is how bright they’d appear at 1 A.U. distant) of +21.3 and is currently well placed for follow up observations in the constellation Virgo.

And astronomer Nick Howes mentioned to Universe Today that the Faulkes Telescope North may soon be used to make further observations of 2014 KM4. In the meantime, you can enjoy the animation of their observations of another Near-Earth Asteroid, 2014 KP4.

An animation of the motion of PHA asteroid 2014 KP4. Credit: Remanzacco Observatory.
An animation of the motion of PHA asteroid 2014 KP4. Credit: Remanzacco Observatory.

And yes, the 2022 pass of 2014 KM4 near Jupiter will modify the orbit of the asteroid… but not in our direction. Jupiter is a great “goal tender” in this regard, protecting the inner solar system from incoming hazards.

2014 KM4 is well worth keeping an eye on, but will most likely vanish from interest until it returns to our neck of the solar system in 2065. And no, a killer asteroid won’t hit the Earth in 2045, as a CNN iReport (since removed) stated earlier this week… on “March 35th” no less. Pro-tip for all you conspiracy types out there that think “Big NASA” is secretly hiding the next “big one” from the public: when concocting the apocalypse, please refer to a calendar for a fictional date that at least actually exists!