4 ms·
Size and albedo of the largest detected Oort-cloud object
- Simon_ORourke 2y ago11AU is close enough thank you very much
- atemerev 2y agoHey, I want another Hale-Bopp, which was at 0.9 AU.
- pmichaud 2y agoAbout 137km diameter, so really big, but albedo (surface brightness, basically) still similar to other comets.
- pfdietz 2y agoThis object is thankfully not coming anywhere close to Earth, but an impact of an object this size with Earth would still not sterilize the biosphere, or even evaporate the oceans.
- BobbyJo 2y ago"Puny rock couldn't even cook every last bacterium on our planets surface. Pathetic." - You
- LeifCarrotson 2y agoThe KT impactor has been estimated to have been about 10 km in diameter and moving at 20 km/s. A long-period comet, like an Oort cloud object, might impact at 50 km/s, instead of the 10-20 km/s of a near-Earth asteroid. The physics might say that the energy might not be enough to literally vaporize the oceans or "sterilize" the biosphere, but the global ecosystem is fragile. This thing dropping on the planet would absolutely cause a mass extinction.
- pfdietz 2y agoOh, I didn't say the results wouldn't be utterly catastrophic. It's more a comment on just how surprisingly large an impact would be needed for sterilization. https://iopscience.iop.org/article/10.3847/psj/ac66e8 https://iopscience.iop.org/article/10.3847/psj/ac66e8 (extrapolated > 700 km impactor needed for sterilization)
- jajko 2y agoI don't think anymore absolutely 100% sterilization of all life on Earth is possible, we always end up talking about 99.999999% or similar. With exception of maybe super/hypernova of our Sun which ain't possible, or black hole passing directly through/very close to Earth, tearing apart every single atom making up this planet including all of us on quark level.
- s1artibartfast 2y agoColision with a planet or moon would do it, anything that turns the surface to lava really.
- sebzim4500 2y agoEven then there's a chance a few tardigrades hibernate on some material that shoots up and then comes back a few years later once the earth has cooled a bit.
- LeifCarrotson 2y agoI propose we do this intentionally - put a few tardigrades and some other extremophiles in a rad-shielded container inside a fully-passive reentry vehicle and throw it up into a graveyard orbit for a couple million years. Cheap insurance for life on earth!
- pfdietz 2y agoI think they could be cooked by thermal radiation as the ejecta expands.
- belter 2y agoMy quick back of envelope calculations... Imply that the kinetic energy released upon the impact of such an object, show a group sheltering at the ISS (orbit at an altitude of between 370–460 km (200–250 nmi)) or the Tiangong (orbit between 340 and 450 km (210 and 280 mi) ) would not be likely to survive the impact from ejecta thrown into their orbital altitude...
- sebastiennight 2y agoOK I'm curious about this bit. How do you deduce the range of height of the ejecta from a calculation of the kinetic energy of the impactor?
- belter 2y agoYou would start with kinetic energy of the impactor using the Kinetic Energy Formula. https://www.calculatorsoup.com/calculators/physics/kinetic.php?given_data=energy&KE_units=joule&m=1.0E%2B16&m_units=kilogram&v=25000&v_units=meter+per+second&sf=0&given_data_last=energy&action=solve https://www.calculatorsoup.com/calculators/physics/kinetic.p... Let's go with 1.0E+16 Kg for mass and 25000 m/s for impact speed what gives about KE = 3.125E+24 J Assume 10% of that goes into ejecta.Then use the formula for Velocity from Kinetic Energy. https://calculator.academy/kinetic-energy-to-velocity-calculator/ https://calculator.academy/kinetic-energy-to-velocity-calcul... What gives about 8000 m/s of initial speed. Follow that using Maximum Height Formula from kinematics based on a Gravitational acceleration at g: 9.8 m/s² https://www.omnicalculator.com/physics/maximum-height-projectile-motion https://www.omnicalculator.com/physics/maximum-height-projec... We are looking at eject reaching orbits of 2500 Km to 3000 Km above Earth. Heat and corresponding vaporization effects excluded for simplification purposes. Now we wait for an event to validate my calculations....
- sebastiennight 2y agoTaki taki, mi belta kopeng!
- perihelions 2y agoIt'd certainly sterilize the vertebrate part of the biosphere: a significant part of its chemical composition (per the paper) should theoretically be CO and HCN. "Hypervolatiles" is the term the paper uses—primordial evils that can only exist in the coldest outer reaches of the Oort cloud, far away from the star that evaporates them. I don't know the exact numbers, but for water ice the "frost line" is at about 3 au (between Mars and Jupiter)[0]—the line inside which icy comets and ice moons, like Europa, can't form. Presumably there's analogous zones for the increasingly volatile cryogenic ices, going out into the most distant regions—a solid carbon dioxide line, a carbon monoxide line, a cyanide line... The surface of Pluto, for example, is mostly solid nitrogen, with parts of solid methane and solid carbon monoxide [1]. [0] https://en.wikipedia.org/wiki/Frost_line_(astrophysics) https://en.wikipedia.org/wiki/Frost_line_(astrophysics) [1] https://en.wikipedia.org/wiki/Pluto#Geology https://en.wikipedia.org/wiki/Pluto#Geology
- cozzyd 2y agoNary a username more apt.
- pfdietz 2y agoI don't think anything beyond the elemental composition of the impactor would matter much since the impact would heat it to a temperature at which it would be in chemical thermodynamic equilibrium, regardless of what its initial molecular composition was.
- hinkley 2y agoIf it’s made of the same stuff as comets, there would be some value to blowing it up, since more parts would then evaporate before impact. Right?
- webdoodle 2y agoIs this the '9th planet' that Batygin and Brown, inferred the existence of based off the orbital tracks of smaller objects in the Oort cloud? https://astrobiology.nasa.gov/news/caltech-researchers-find-evidence-of-a-real-ninth-planet/ https://astrobiology.nasa.gov/news/caltech-researchers-find-...
- perihelions 2y agoNo; it's about 30 million times too small. :)
- Tuna-Fish 2y agoNo, this is way too small and close for that.
- d_silin 2y agoI wonder if we can get a flyby mission by 2031 from NASA or ESA.
- AlphaEsponjosus 2y agoI wonder if NASA will still existing in 2028.
- chgs 2y agoNasaX, or maybe NAXA or something.
- Nevermark 2y agoWell XASA obviously! The government would save billions (tens of billions over the long haul), increase cadence, increase mission scope, and cut flight times, by cutting NASA’s build-&-burn rocket manned program in favor of SpaceX’s reusable manned craft and space refueling services. SpaceX Starship could also reduce the cost and increase cadence of scientific missions, in two ways: 1) By reducing launch costs via greater system reuse. 2) And by increasing available launch volume, eliminate a lot of the design & manufacturing time, cost, complexity and risk created by today’s need to fit craft into toad’s more limited volumes. Less need for craft miniaturization means (a) fewer risky/complex unfolding maneuvers in flight, (b) much easier radiation mitigation via more shielding, larger more resilient circuits, redundancy, etc. And (c) fewer craft, with more capabilities and higher longevity. And as with the manned program, increase mission scope, while reducing transfer to target times, via in orbit refueling. If only we could find someone with the incentives, plan, means and mandate, to cut government space spending while somehow also expanding its manned & scientific space exploration capabilities and scope. The hardest part is to find such a uniquely capable person, who also has enough slack time to take this on. A rare trait combination, indeed. What are the chances of finding a genius reefer doom scrolling bloviating slacker? Who could put all that disposable time to better use?
- Nevermark 2y ago
- didgetmaster 2y agoFor comets or other objects whose perihelion is less than 1 au; does the chance of collision with Earth increase if the orbit is within the elliptical plane vs outside it?