Amazing Space Shuttle Shot. 🚀

September 15

This one is technically not yet history, because at the time of posting, the little craft has about half an hour left to go.  That said, let’s proceed.

In 2017, NASA’s Cassini space probe ended its twenty-year mission at Saturn.  After a nearly-seven-year-long journey there, it orbited the ringed planet for 13 years and just over two months, gathering copious amounts of information about the planet, said rings, and many of its moons.  It landed an ESA probe called Huygens on Titan, the first-ever soft landing in the outer Solar System.  It discovered lakes, seas, and rivers of methane on Titan, geysers of water erupting from Enceladus (and passed within 50 miles of that moon’s surface), and found gigantic, raging hurricanes at both of Saturn’s poles.  

And the images it returned are beautiful enough to make you weep.

On this day in 2017, with the fuel for Cassini’s directional thrusters running low, the probe was de-orbited into the Saturnian atmosphere to prevent any possibility of any contamination of possible biotic environments on Titan or Enceladus.  The remaining thruster fuel was used to keep the radio dish pointed towards Earth so the probe could transmit information about the upper atmosphere of Saturn while it was burning up due to atmospheric friction.

This is us at our best.  We spent no small amount of money on a nuclear-powered robot, launched it into space, sent it a billion miles away, and worked with it for two decades just to learn about another planet.  And when the repeatedly-extended missions were through, we made the little craft sacrifice itself like a samurai, performing its duty as long as it could while it became a shooting star in the Saturnian sky.

Rhea occulting Saturn

Water geysers on Enceladus

Strange Iapetus

Look at this gorgeousness

A gigantic motherfucking storm in Saturn’s northern hemisphere

Tethys

This image is from the surface of a moon of a planet at least 746 million miles away.  Sweet lord

Mimas

Vertical structures in the rings.  Holy shit

Titan and Dione occulting Saturn, rings visible

Little Daphnis making gravitational ripples in the rings

That’s here.  That’s home.  That’s all of us that ever lived.

Saturn, backlit

A polar vortex on the gas giant

Icy Enceladus

(All images from NASA/JPL)

What Separates A Good Scientific Theory From A Bad One?

“It’s why an idea like dark matter is so powerful. By adding just a single new species of particle — something that’s cold, collisionless, and transparent to light and normal matter — you can explain everything from rotating galaxies to the cosmic web, the fluctuations in the microwave background, galaxy correlations, colliding galaxy clusters, and much, much more. It’s why ideas with a huge number of free parameters that must be tuned to get the right results are less satisfying and less predictively powerful. If we can model dark energy, for instance, with just one constant, why would we invent multi-field models with many parameters that are no more successful?”

You’ve often heard, when discussing competing scientific ideas, of appealing to Occam’s razor. Often paraphrased as “all things being equal, the simplest explanation is usually best,” it seems to open the door for people to argue over which explanation is simplest. This should not, however, be a point of contention: the explanation that’s simplest is the one that introduces the fewest number of new, additional free parameters. And when it comes to all things being equal, the things in question ought to be the number of new phenomena the novel idea can explain, along with the number of discernible predictions as compared with the old, prevailing idea. The best scientific ideas are the ones that explain the most by adding the least, while the worst ones unnecessarily add additional parameters on top of what we observe for no good reason other than personal bias. Ideas may be a dime-a-dozen, but a good idea is hard to find.

The next time you encounter an interesting, wild idea that someone throws out there, use this criteria to evaluate it. You just might be surprised at how quickly you can tell whether an idea is good or bad!

The Planets (BBC) - Jupiter and Io

Image of Saturn taken by Cassini spacecraft in October 28, 2016.

Credit: NASA/JPL 

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 It was time for their close-up. Two days ago Jupiter and Saturn passed a tenth of a degree from each other in what is known a Great Conjunction. Although the two planets pass each other on the sky every 20 years, this was the closest pass in nearly four centuries. Taken early in day of the Great Conjunction, the featured multiple-exposure combination captures not only both giant planets in a single frame, but also Jupiter's four largest moons (left to right) Callisto, Ganymede, Io, and Europa -- and Saturn's largest moon Titan. 

Image Credit:  Damian Peach

Jupiter and Europa

Charon, moon of Pluto, observed by NASA’s New Horizons probe on this day in 2015.

Juno: Movie of clouds on Jupiter, taken with the JIRAM infrared camera.

Arthur Strengthens, Moves Northward by NASA Goddard Photo and Video