To Cut Odds of a Big Bang on Earth, Heed Jupiter's Flashing Warning Sign

The citizen-science effort tracking Jovian collisions could help humanity avoid the fate of the dinosaurs.

Sep 16, 2021

You may have heard passing news about a flash on Jupiter. Here's a deeper look at why this stray observation matters if you're eager for a long productive human journey on planet Earth.

On Monday, September 13th, a digital camera mounted on a modest telescope in a back yard on the outskirts of Sao Paulo, Brazil, recorded a small, fleeting burst of light on the gaseous face of Jupiter. It took until Tuesday for the telescope's operator, José Luis Pereira, to get confirmation that the flash was the explosive result of an impact by an asteroid or comet.

Pereira, a self-described "assiduous planetary observer," is part of a small, dedicated world-spanning network of hundreds of amateur astronomers and "astrophotographers" watching for stray moments when a comet or asteroid collides with the solar system's biggest planetary targets. (They also watch Saturn.)

Just a few of the planet watchers contributing to the Impact Flashes Detection Project using DeTeCt software (Marc Delcroix)

In a memo to journalists and fellow skywatchers, Pereira said he wasn't aware of the flash (or its significance) at the time of the event. Such features are so subtle that a computer program, DeTeCt, is used to analyze video after the fact. He had started the software running before he went to bed and sent the information to Marc Delcroix, one of the managers of the project, who confirmed the discovery and helped process this image:

The bright spot marks where a small comet or asteroid struck Jupiter on September 13 ( José Luis Pereira, processed by Marc Delcroix)

"For me it was a moment of great emotion as I have been looking for a record of this event for many years," Pereira wrote. (Subscribe to his YouTube channel and Flickr account.)

For the rest of us, Pereira's observation of this collision is an invaluable addition to an urgent effort to clarify cosmic risks facing Earth and its inhabitants.

Along with helping reveal the chemistry of the atmosphere of our giant neighbor, observations of such collisions can help scientists and space agencies refine understanding of the frequency and intensity of what is coming Earth's way someday.

And something is coming our way, as is clearly illustrated by the many impact craters around this planet.

Barringer Meteor Crater near Flagstaff, Arizona, formed by an asteroid impact 50,000 years ago. (USGS photo)

Pursuing a sustainable journey for humanity and our thriving Earth is not just about fostering a better relationship with climate and ecosystems. It is also about avoiding the fate of the dinosaurs. I began writing about this – the ultimate example of a rare but high-impact hazard – in The New York Times many years ago and will keep at it here.

At the bottom of the post you can find more details on the September 13 collision and a batch of additional resources. But let's get to some wider context first.

Jupiter as flashing warning sign

Fragments of Comet Shoemaker-Levy 9 bombarded Jupiter in 1994, offering a sobering wakeup call to prepare Earth for such events. Compare the atmospheric "bruise" at left with the rough size of Earth at right.

Jupiter's role as a warning beacon for the asteroid and comet threat dates from 1994. The astronomers who discovered Comet Shoemaker-Levy 9 in 1993 also predicted the collision of its fragments with the planet (Jupiter's gravitational force pulled it apart). That advance notice made it possible to deploy powerful tools ahead of time and record the collisions in stunning detail.

As Lindley Johnson, NASA's first planetary defense officer, put it in a great 2019 NASA article, “The Shoemaker-Levy 9 event showed us that we are vulnerable to impacts in the present day, not just in the distant past... These impact events occur in the Solar System right now, and we should do our best to find hazardous objects before they are of imminent danger of impacting Earth.”

Since then, through the dogged efforts of former astronauts, planetary scientists and others, the world has slowly moved from research on the risk posed by big incoming rocks (and a batch of fanciful disaster movies) to devising a response.

As the Planetary Society has explained, there are five steps to risk reduction facing this profound but challenging kind of hazard - find, track, characterize, deflect, coordinate and educate.

That means the response is not just developing physical systems that might be able to change the course of an asteroid once a killer is identified. It's also vital to have global protocols and awareness to limit losses on the ground if the worst happens.

Signs we might get this right

Here are two signs we might be inching toward getting this existential threat right - a rare thing given humanity's "blah, blah, blah, bang" approach to disaster preparedness.

Deflect

On November 24, after years of planning and a few delays, the latest launch window will open for NASA's Double Asteroid Redirection Test, or DART for short. The DART spacecraft will head to a nearby binary asteroid system (one not threatening Earth) and, sometime in September or October of 2022, collide with the smaller asteroid, Dimorphos, with sufficient force to change its orbit around the main asteroid, Didymos. The change will demonstrate the potential of the technique.

A rendering of the DART mission shows the spacecraft's planned impact on the moonlet of asteroid Didymos. (NASA/Johns Hopkins Applied Physics Lab)

Of course this is just one of many possible strategies. As the Planetary Society has described, DART is kind of the middle path - neither explosive destruction nor a gentle nudge. At around $320 million over eight years, I see the mission as a profound bargain, and planetary defense remains a tiny sliver of NASA's overall budget.

Coordinate and educate

In January, 2010, I was honored to be invited by the former Apollo astronaut Rusty Schweickart, long a champion of action on near-Earth objects, to play the role of the journalist in a tabletop asteroid-response exercise held in Mexico City. Others played roles of diplomats, scientists, defense leadership, politicians and the general public. It was a small-scale paper and pencil affair, but still led to invaluable insights - the most important being that the world needs much clearer protocols for cooperative responses under wrenching scenarios that might emerge when a catastrophic threat was identified.

In April this year, NASA led a far more sophisticated four-day asteroid-impact exercise at the International Academy of Astronautics Planetary Defense Conference in Vienna, which had this cheery website homepage image:

I encourage you to explore the day-by-day summaries as the detailed scenario played out.

Day two looked particularly rough for Europe. This forecast made me happy Earth is in a fairly placid space environment. Imagine if NASA had to put out asteroid forecast cones of uncertainty like those the National Hurricane Center posts each year?

By the final day the risk modulated. But there was still drama given that the final impact was for this October.

A graphic from the bulletin for the final day of an international exercise aimed at improving asteroid preparedness.

The key recommendation? Earlier investments in systems to find, track and characterize potential colliders can greatly widen the list of response options.

A last look at the latest Jupiter flash

The object recorded on Monday was almost assuredly very small given that no evidence of the collision persisted in the Jovian atmosphere even an hour later, according to the planet-watching astronomer Damian Peach on Twitter. The astronomer Heidi Hammel added that "initial estimates put this object at less than 40 meters (130 feet) across."

I reached out for an update from Ricardo Hueso Alonso, a physicist who co-runs the network with Marc Delcroix and lectures at the University of the Basque Country near Bilbao, Spain.

He said the latest event is the seventh Jupiter impact discovered so by amateur astronomers. (Explore others here.)

Pereira's wasn't the only view, he added. "The current event is the brightest and the one that has been observed by most people: 1 from Brazil, 2 for Germany, 3 from France, 1 from Italy."

He noted one other important benefit in recording as many Jupiter impacts as possible. "Observing impacts in Jupiter helps to understand the physics of airbursts" - the high-energy explosions that occur when high-velocity objects penetrate the Jovian atmosphere. The observations help refine models of how such an event will play out in Earth's atmosphere, as well.

p.s., Jupiter isn't a shield

Here’s an important final thought. There’s been an enduring hypothesis that Jupiter’s powerful gravitational field has helped shield Earth from cosmic collisions by acting like a big vacuum cleaner for threats coming into the inner solar system.

But recent research by planetary physicist Kevin Grazier and others, using observations and simulations, is eroding any comfort factor. George Dvorsky at Gizmodo recently covered the new studies and included this sobering comment from Grazier: “Our simulations show that Jupiter is just as likely to send comets at Earth as deflect them away, and we’ve seen that in the real solar system."

For more on the overall asteroid and comet threat and response options, watch Apollo astronaut Rusty Schweickart's great NASA presentation: Dinosaur Syndrome Avoidance Project: How Gozit?

Here's a presentation by Marc Delcroix on the Jupiter monitoring network and software (in French, but with English auto translation):

I can't wait to see what filmmaker Adam McKay has in store in "Don't Look Up," his Netflix-financed Christmas release in which Leonardo DiCaprio plays one of "two low-level astronomers who must go on a giant media tour to warn mankind of an approaching comet that will destroy planet Earth.”

The trailer is out: