We're going to need a Bigger Bomb ...Asteroids are Stronger, Harder to Destroy than Previously Thoughthttps://phys.org/news/2019-03-asteroids-stronger-harder-previously-thought.html A popular theme in the movies is that of an incoming asteroid that could extinguish life on the planet, and our heroes are launched into space to blow it up. But incoming asteroids may be harder to break than scientists previously thought, finds a Johns Hopkins study that used a new understanding of rock fracture and a new computer modeling method to simulate asteroid collisions.
... The new model showed that the entire asteroid is not broken by the impact, unlike what was previously thought. Instead, the impacted asteroid had a large damaged core that then exerted a strong gravitational pull on the fragments in the second phase of the simulation.
The research team found that the end result of the impact was not just a "rubble pile—a collection of weak fragments loosely held together by gravity. Instead, the impacted asteroid retained significant strength because it had not cracked completely, indicating that more energy would be needed to destroy asteroids.
Armageddon (1998) - RockHound
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There May Be 50 Billion Rogue Planets in Our Galaxyhttps://www.popularmechanics.com/space/deep-space/a26788244/milky-way-rogue-planets/According to a new simulation of star behavior, a staggering number of planets aren’t orbiting any star at all. Instead, there could be 50 billion rogue planets are adrift in the Milky Way.Rogue planets have been known to science for a while. Astronomers for centuries have suspected that rogue planets exist, and in recent years we’ve even found a few of them. But as a class, rogue planets are still somewhat of a mystery.
To get past these hurdles, a group of astronomers at the University of Leiden built a simulation of 1,500 stars in a real place called the Orion Trapezium star cluster. About 500 of these simulated stars contained between four and six planets, giving the sim a grand total of 2,522 planets. When the scientists ran the simulation forward, they found that gravitational effects from the closely packed stars kicked about 350 of those planets outside their respective star systems.
If that’s the case, and you extrapolate that result across the Milky Way, then there could be billions of rogue planets careening throughout the galaxy undetected.
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Exiled Planet Linked to Stellar Flyby 3 Million Years Agohttps://www.sciencedaily.com/releases/2019/02/190228093551.htm Two binary star systems narrowly missed one another, but left behind a smoking gunPaul Kalas of UC Berkeley was puzzled by the tilted but stable orbit of a planet around a binary star -- an orbit like that of our solar system's proposed Planet Nine. He calculated backwards in time to see if any of the 461 nearby stars ever came close enough to perturb the system. One star fit the bill. The stellar flyby 2-3 million years ago likely stabilized the planet's orbit, keeping it from flying away.
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Astronomers Just Discovered Two Rogue Planets in Our Galaxyhttps://www.sciencealert.com/these-lonely-planets-drift-through-space-without-orbiting-starsPolish astronomers just discovered two new planets in our galaxy. That's cool news on its own, but these planets are different from most. Unlike almost all known planets, New Scientist reports, these two planets don't orbit a star.
To spot these two new wanderers, Warsaw University astronomers used a technique called gravitational microlensing.
Their research, published last week on the preprint server ArXiv, describes how they used the technique to find points where the light of faraway stars was warped and distorted by the gravitational pull of a planet that had drifted in that light's path.
Because the evidence of these two planets is so circumstantial, scientists aren't sure how large they are. Depending on how far away they are,
New Scientist noted that one of the planets could be anywhere from two to 20 times the mass of Jupiter.
The other one is anywhere from 2.3 to 23 times more massive than Earth.
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This Massive "Rogue" Planet is Our Solar Neighborhttps://www.popularmechanics.com/space/a22705121/this-massive-rogue-planet-is-our-solar-neighbor/In 2016, scientists discovered a massive floating object in our galactic neighborhood. It was more than 12 times the size of Jupiter (the biggest planet in our solar system), with a magnetic field that was 200 times more powerful. The mass lived just 20 light years outside of our solar system. Unlike Jupiter and other planets that orbit around a parent star, this space oddity was completely rogue.
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... and because you always wanted to know ...What Would It Feel Like On the Surface of Earth if It were to Collide with Another Planet?https://worldbuilding.stackexchange.com/questions/40193/what-would-it-feel-like-on-the-surface-of-a-planet-while-it-collides-with-anothe Cool Video - Discovery Channel - Large Asteroid Impact Simulation:
Assumption: A planet the size of Mars slams into the Earth:The slowest possible approach of the rogue to the earth would occur with a Hohmann transfer orbit, and in this case orbital energies dictate a closing speed of about 3 km/sec. However, this ignores the gravitational attraction between the earth and the rogue, which will boost this closing speed to about 9.5 km/sec. Time to contact from 10 times the moon's orbit is about 14 days. At this distance, the area of the rogue's disk is about 1/50 that of the moon.
Time to impact from crossing the moon's orbit is about 27 hours. A this point tides are about 8 times greater than normal. So, no massive tsunamis until a few hours before impact, and this will affect only small part of the earth. There will be a tidal bulge at impact of about 100 km.
Furthermore, since the orbit is essentially tangent to the earth's orbit, it will appear in the sky at 90 degrees from the sun, directly overhead at dusk, and will present a "half-moon" appearance.
Since the earth's atmosphere is about 30 km deep, the rogue will not appreciably affect the earth's atmosphere until less than 5 seconds before impact. No vortex. With a relative velocity near 10 km/sec, a tangent path from sea level to 30 km is about 2,000 km, so for a near-miss the atmosphere will be affected for a duration of (at most), about 3 minutes. No hoovering. Just an enormous shock wave.
Since Mars' surface gravity is about 40% that of earth, just at contact the apparent gravity at ground zero will be reduced to about 27% of normal. No floating. And on the other side of earth things get heavier by about 3%. No crushing gravity, I'm afraid.
Centrifugal force will be irrelevant, and there will be no swirling water. A head-on collision (well, head to tail) will simply liquefy the two bodies. The collision zone will be, especially at first, expanding hypersonically away from the point of impact.
The folks on the far side of the planet will not have to wait a day to feel things, as the shock wave will propagate through the planet in less than 20 minutes.
Well, OK, everybody dies.If, somehow, the rogue is thrown into an orbit which meets the earth head-on, the closing speed will be about twice the earth's orbital velocity (plus a bit for gravitational attraction), or about 60 km/sec. This is even quicker and more spectacular. But in the end, everybody dies.
Since the actual impact will only last minutes, on the far side it will be kinda like this as the shockwave approaches:
T-10 minutes: 20C and sunshine
T-5 minutes: 20C and sunshine
T-4 minutes: 20C and sunshine
T-3 minutes: 20C and sunshine
T-2 minutes: 20C and sunshine
T-1 minute: 20C and sunshine (is that a shadow on the horizon?)
T-0 minutes: 4,000 C and death.--------------------------------------------
http://universesandbox.com/11 minutes post impact 29 minutes post impact