Anyone who’s ever seen a map or a globe easily knows that the surface of our planet is mostly covered by liquid water — about 71%, by most estimates* — and so it’s not surprising that all Earthly life as we know it depends, in some form or another, on water. (Our own bodies are composed of about 55-60% of the stuff.) But how did it get here in the first place? Based on current understanding of how the Solar System formed, primordial Earth couldn’t have developed with its own water supply; this close to the Sun there just wouldn’t have been enough water knocking about. Left to its own devices Earth should be a dry world, yet it’s not (thankfully for us and pretty much everything else living here.) So where did all the wet stuff come from?
As it turns out, Earth’s water probably wasn’t made, it was delivered. Check out the video above from MinuteEarth to learn more.
*71% of Earth’s surface, yes, but actually less total than you might think. Read more.
MinuteEarth (and MinutePhysics) is created by Henry Reich, with Alex Reich, Peter Reich, Emily Elert, and Ever Salazar. Music by Nathaniel Schroeder.
It’s no mystery that the planets, moons, asteroids, etc. in the Solar System are arranged in a more-or-less flat, plate-like alignment in their orbits around the Sun.* But why is that? In a three-dimensional Universe, why should anything have a particular alignment at all? In yet another entertaining video from the folks at MinutePhysics, we see the reason behind this seemingly coincidental feature of our Solar System — and, for that matter, pretty much all planetary systems that have so far been discovered (not to mention planetary ring systems, accretion disks, many galaxies… well, you get the idea.) Check it out above.
If you go out hiking this weekend and somehow find yourself hopelessly lost in the wilderness, but suddenly remember you have a compass with you, you can use it to find north because the needle always points towards the Earth’s geographic north pole, which never changes… right?
Wrong, wrong, and wrong. And this video from MinutePhysics explains why.
(But still bring a compass with you. They do come in handy.)
How old is the Earth, how long did it take for life to appear, and how long would it take for your hair to grow to the Moon? Find out in this video from MinuteEarth (a new project by MinutePhysics’ Henry Reich):
(Because you always wanted to know how long it would take for your hair to grow to the Moon — admit it.)
And be sure to check out MinuteEarth’s newest video Why Are Leaves Green?Part 1 and Part 2.
When the Apollo boys visited the Moon back in the ’60s and ’70s they left more than just some experiments, rovers, and family portraits behind –- they also left, shall we say, a little bit of themselves on the lunar surface. It makes total sense when you think about it, but still… there’s poop on the Moon.
In this video, Minute Physics and Destin from Smarter Every Day show how astronauts would relieve themselves during the Apollo missions (or at least the gadgets they used — we all know how they did it) and why it was decided to make astronaut poop a permanent part of their lunar litter.
(Because there’s no public toilets in the Sea of Tranquility.)
In another video Destin goes on to discuss some of the other things the Apollo astronauts left on the lunar surface as part of their… duties… most notably the Laser Ranging Retroreflectors that are still being used today to measure distances between Earth and the Moon. Destin explains how their corner-cube reflectors work — using, fittingly, the mirrors in a restroom shared with NASA at the University of Alabama at Huntsville. Check out the video below.
According to the Lunar and Planetary Institute: “The Laser Ranging Retroreflector experiment has produced many important measurements. These include an improved knowledge of the Moon’s orbit and the rate at which the Moon is receding from Earth (currently 3.8 centimeters per year) and of variations in the rotation of the Moon. These variations in rotation are related to the distribution of mass inside the Moon and imply the existence of a small core, with a radius of less than 350 kilometers, somewhat smaller than the limits imposed by the passive seismic and magnetometer experiments. These measurements have also improved our knowledge of changes of the Earth’s rotation rate and the precession of its spin axis and have been used to test Einstein’s theory of relativity.”
Want to see how corner-cube reflectors work? Click here.
The Laser Ranging Retroreflector experiment deployed on Apollo 11 (NASA)
Just goes to show that not everything that got left behind was crap.
See more videos from Destin at Smarter Every Day here and more Minute Physics here.
How do magnets affect things at a distance? How does the Sun heat our planet from 93 million miles away? How can we send messages across the world with our cell phones? We take these seemingly simple things for granted, but in fact there was a time not too long ago when the processes behind them were poorly understood, if at all… and, to the uninformed, there could seem to be a certain sense of “magic” about them.
This video from MinutePhysics, featuring director of the Perimeter Institute for Theoretical Physics Neil Turok, illustrates how our understanding of electromagnetic fields was developed and why there’s nothing magic about it… except, perhaps, how they pack all that excellent info into 5 minutes. Enjoy!