Aftermath of the Biggest Explosion Ever Caught on Camera | Shoemaker-Levy 9

Thanks to Neeva for sponsoring today’s video.   In July of 1994, scientists around the world  watched in amazement as the comet Shoemaker-Levy   9 smashed into Jupiter. The impact’s blast was so  powerful that it unleashed a force equivalent to   300 million atom bombs. For six days, Jupiter  was throttled by 21 separate impacts from the   comet’s fragments, which produced giant plumes  of debris that rose 3,000 kilometres above the   cloud tops – an impressive feat considering  Jupiter’s immense gravity - and heated Jupiter’s   atmosphere to temperatures reaching 30,000  degrees Celsius. At the moment of impact,   the comet was travelling at a blistering speed  of 216,000 kilometres per hour, with its largest   fragment spanning 2 kilometres in diameter. The  impact raised huge clouds of debris that were   visible for months and left a scar in Jupiter’s  atmosphere more prominent than its Great Red Spot.   Now, collisions of this magnitude aren’t  entirely unheard of. Our Solar System is   littered with evidence of major impacts  from comets and asteroids. Scientists   believe Earth was hit by a massive asteroid  at the end of the Cretaceous Period, which   likely led to the extinction of the non-avian  dinosaurs. But these events are extremely rare,   meaning the chance to see one in action is a  once-in-a-lifetime opportunity. So, what did it   look like? And does the incident shed light on the  odds of a similar event happening here on Earth?   I’m Alex McColgan, and you are watching Astrum.  Join me today as we relive the biggest planetary   explosion ever witnessed from space – and unpack  what it taught us about Jupiter and planetary   collisions. In 1993, astronomers Carolyn and  Eugene Shoemaker and David Levy were conducting   research at California’s Palomar Observatory  when they discovered a periodic comet that had   been captured by Jupiter’s gravitational pull.  (“Periodic” means the comet has an orbital period   of fewer than 200 years.) This was unusual, as  most comets in our Solar System orbit the Sun.   However, Jupiter is so massive, being the  largest of the eight planets by far, that   its ability to capture other objects approaching  its orbit isn’t surprising. A lot of Jupiter’s   irregular moons are likely captured asteroids and  comets that have since burned off their volatile   material on their surfaces. But this comet also  had other unusual characteristics. For one, it was   big. So big that scientists think the frequency of  similar impacts is a one-in-6,000-year occurrence.   But the comet was also fragmented, most  likely torn apart by Jupiter’s tidal   forces on a previous approach. Most striking of  all, however, was its highly eccentric orbit.   Eccentricity measures the deviation of an orbit  from a circle, with zero being the value of a   perfect circle and one being the upper limit  when an elliptical orbit becomes hyperbolic.   Shoemaker-Levy 9’s orbit had an eccentricity of  over .998: in other words, extremely eccentric.   Almost immediately, astronomers realized there  was a possibility the comet could collide   with Jupiter, but their suspicion turned into  certainty once they collected more precise data.   Before long, astronomers knew the impact would  occur sometime in July 1994, and pretty soon the   whole world was waiting for the event with bated  breath. Anticipating SL9’s impact, astronomers   monitored its movements from the Keck Observatory,  Germany’s ROSAT X-ray telescope and NASA’s Hubble   Space Telescope among other instruments. But when  the first of the comet’s fragments hit on July 16,   1994, the worst case scenario occurred, it  looked like we would miss the spectacle!   You see, SL9’s trajectory meant the impact would  occur on the side of Jupiter facing away from us.   That meant none of Earth’s high-powered telescopes  were in position to view the initial impact.   For scientists, this would have been a crushing  disappointment. But as luck would have it,   not all our cameras were located here on Earth.  By sheer chance, NASA’s Galileo spacecraft,   launched in 1989, was only one year out from  Jupiter at the time of SL9’s final approach.   It just so happened to be in perfect  position to record the impact as it happened.   But Galileo wasn’t our only helper  from afar. The Ulysses spacecraft,   which had been launched in 1990 to monitor  the Sun, was also pointed at Jupiter.   And even NASA’s Voyager 2, located 44 Astronomical  Units away (or 6.6 billion kilometers), was   programmed to monitor radio emissions from the  crash site with its ultraviolet spectrometer. Each   probe paused its own missions to work together on  this to help us witness an extraordinary event.   Shortly after Fragment A impacted Jupiter,  Galileo saw a massive fireball erupt,   reaching temperatures as high as 24,000 degrees  Celsius. Its plume quickly rose 3,000 kilometres,   which would make it as big as Australia from  north to south! This was surprising, as scientists   hadn’t expected to see fireballs in the aftermath  of the collision. A few minutes later, masses of   ejected debris plummeted back toward Jupiter’s  surface and burned up, again turning Jupiter’s   atmosphere into a raging furnace. Before long,  Jupiter’s rotation brought the impact site into   view of Earth, allowing high-powered telescopes  like Hubble to view a huge dark spot on Jupiter.   (As it happens, Jupiter’s rotation is fast,  with days that last only 10 hours. Contrary   to what you might think, larger planets tend  to have shorter days than smaller ones!)   The comet’s impact set off shockwaves, which  rippled across Jupiter’s dense atmosphere at   a speed of 450 meters per second. And all this  was just from the first impact. For six days,   between July 16th and July 22nd, the comet’s  fragments bombarded Jupiter, the largest coming   on July 18th, when Fragment G hit. Its impact  alone produced a blast 600 times more powerful   than the world’s entire nuclear arsenal, leaving  a huge dark spot one Earth diameter across.   However, as spectacular as the initial impact was,  the comet’s aftermath proved just as valuable. By   studying the clouds of debris, scientists gained  an unprecedented window into Jupiter’s atmosphere   and its movements. In addition, they caught a  never-before-seen glimpse of Jupiter’s composition   beneath its dense cloud tops, as spectroscopic  readings were able to identify material that had   been splashed upward by the comet’s impact. They  detected diatomic sulfur and carbon disulfide, and   heavy elements like silicon, iron and magnesium.  Interestingly, they also detected substantial   amounts of water, something they weren’t  necessarily expecting. In fact, one of NASA’s Juno   probe’s primary objectives is to locate where this  water is hiding in Jupiter’s atmosphere. However,   one of the more disturbing implications of the  impact was the realization that large celestial   bodies could still hit planets. One school of  thought theorized that major comet and asteroid   collisions had been a lot more frequent earlier in  the Solar System’s existence. But Shoemaker-Levy   9 made it clear that very destructive collisions  were still possible. Had it happened by chance,   and we witnessed an extremely rare event? Or  does it happen more than we thought? Remember,   we’ve only had the technology to see this  kind of event within the last 80 or so years.   If a comet as large as SL9 were to crash here  on Earth, it would lead to the extinction of   most life on the planet. This had a dramatic  effect on our collective psyche, as anyone who   lived through the 1990s can attest! It was also  a wakeup call for NASA and for various defence   agencies. Before SL9, the term “planetary defence”  didn’t exist. But in its wake, NASA took up the   mission of monitoring Near Earth Objects, or NEOs,  with the goal of identifying upwards of 90% of   asteroids in our celestial neighbourhood greater  than 1 kilometre in diameter. Having achieved   this goal, NASA is now well on its way toward  identifying asteroids greater than 140 meters.   But before you stay up all night worrying, be  aware that these events are undoubtedly rare.   And there is, perhaps, one other silver lining  to SL9’s impact... You see, Jupiter is a massive   planet with a powerful gravitational influence,  and since it is also one of the outer planets,   some scientists now think it might act  as a cosmic “vacuum cleaner” of sorts.   We know that Jupiter gets approximately 2,000 to  8,000 times as many cometary impacts as Earth.   So, perhaps one of the reasons extinction-level  impacts are so uncommon here on Earth is that   Jupiter has been a magnet for these kinds of  comets and asteroids. This argument has even   become part of the Rare Earth Hypothesis, which  suggests that Earth is host to a unique set   of conditions, without which the evolution of  complex life would be impossible. Not everyone   agrees with this hypothesis though, and in any  event, we’re still a long way from proving it.   So, while we may not know the exact likelihood of  a massive comet or asteroid hitting the Earth, the   impact of SL9 with Jupiter has certainly advanced  our understanding of these events. Moreover, it   was, without question, a spectacular moment that  treated watchers to one of the most impressive   action scenes ever witnessed by human eyes. Maybe  one day we’ll have the chance to see something   bigger, but hopefully not from too close! While  there have been other explosive events, like the   2022 Tonga volcanic eruption, for now, the winner  is clear: the biggest explosion ever seen on a   planet is Shoemaker-Levy 9. And by comparison,  the competition looks like a drop in the bucket.   When I’m researching my videos, having a good  search engine is vital. 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If you enjoyed  this video, check out my other comet   videos in this playlist here. And  thanks to my patrons and members,   if you want to support the channel too, check the  links below. All the best, and see you next time.

Channel: Astrum

Views: 1,204,391

Keywords: shoemaker levy 9 impact, shoemaker levy, shoemaker levy 9 impact footage, comet impact, largest explosions ever, largest explosion, comet hitting planet, jupiter, shoemaker levy 9 impact earth, comet, nasa, shoemaker-levy 9, shoemaker-levy, comet shoemaker–levy 9, space documentary, shoemaker levy 9 documentary, shoemaker levy 9 jupiter impact, comet shoemaker-levy 9, shoemaker levy 9, comet shoemaker levy hitting jupiter in 1994, 1994, impact, comet strike, space, jupiter planet

Id: wWUx2MnwqlA

Length: 11min 37sec (697 seconds)

Published: Mon Oct 24 2022

Reddit Comments

[u/calcul8r]

I like how they estimate the speed of the comet at 216,000 kph but then convert it mph at six digits of precision.