Fantasist & Futurist
- Nov 23, 2002
1. Asteroids - they all look the same to me...
NASA's OSIRIS-REx mission to the near-Earth asteroid Bennu is almost in position - and it's latest photo reveals that Bennu looks remarkably similar to the asteroid Ryugu, which the Japanese mission is currently in orbit around. Check the image above for a comparison to both.
According to Phil Plait at Bad Astronomy, basic physics has shaped both: Hey Bennu, have we met? I never forget an asteroid.
That’s no coincidence! Both are small, with very weak gravity. Both are also rubble piles: Not solid, monolithic objects but instead like bags of rocks held together by their own gravity. Billions of years of slow-speed collisions have essentially shattered them in place.
The important bit here is that both rotate relatively rapidly. Bennu spins once every 4.3 hours, and Ryugu once every 7.6 hours. That means that a rock sitting on the surface feels a weak pull downward toward the center due to gravity, but also a weak centrifugal force outward, away from the spin axis of the asteroid. These combine such that the equator feels like it’s downhill.
2. Kepler fails, Dawn ends, no word from Opportunity
It's been a bad couple of week's for NASA.
The Kepler telescope, which was already running years past it's end date - it's mission to find planets around other stars - is finally confirmed to have run out of fuel: Kepler telescope dead after finding thousands of worlds and NASA retires Kepler Space Telescope
It's not the only one - the Dawn mission, which saw NASA successfully put a spacecraft in orbit around two asteroids between Mars and Jupiter, has also run out of fuel, and will be left to remain in orbit around Ceres: Dawn mission to asteroid belt comes to end
There's still no word back from the Opportunity rover on Mars, which found itself facing a planet-wide dust storm. However, NASA has yet to give up on the mission: NASA will keep trying to contact stalled Mars rover Opportunity
All three missions have been massive successes that ran well past the time they were designed for - but it's still sad to see a string ending around the same time.
3. Our hungry galaxy
Burp! The Milky Way ate another galaxy. Except this latest merger event probably happened about 10 billion years ago: The Milky Way ate another galaxy, and we can still see the undigested bits
It's now reasonably certain that a number of smaller galaxies have already merged with our Milky Way - and it continues to surprise us. An announcement this week suggested one of the oldest possible stars has also been found within it: Scientist finds elusive star with origins close to Big Bang
4. 'Oumaumau click bait goes viral
A research team working on solar sails for Harvard suggested the possibility that 'Oumaumau - our first proven extra-solar visitor, spotted last year - showed similar properties to a solar sail.
The claim wasn't peer-reviewed and seemed like an obvious click-bait promotion.
However, it does underline one of the particular mysteries of 'Oumaumau - it's apparent acceleration away from our solar system. Some scientists think this was due to gas venting, presuming that 'Oumaumau was a comet - but no comet debris was ever observed.
Phil Plait gives the run-down on this: Is 'Oumuamua an interstellar spaceship? I'm still going with 'no.'
Curiously, I think another article published this week could offer a clue: New insights on comet tails are blowing in the solar wind. Though no-one's apparently made a connection , it might be more plausible to suggest 'Oumaumau contained ferrous-magnetic metals - which might have been given a small kick by our Sun's magnetic field, and therefore explain the change in acceleration. The jury remains out.
5. Bright black holes
Astronomers think they have images of black holes merging in other galaxies Astronomers find pairs of black holes at the centers of merging galaxies
6. Panspermia rocks!
A recent study looked at how life may have travelled between planets - specifically in the Trappist system, famous for its 7 big planets: Sharing life with the planets next door
Warning: some people may be alarmed by the mention of Panspermia!
BONUS! Dinosaurs had colourful eggs: Jurassic world 'more colourful than thought'