Andy Weir is the author of The Martian and Artemis, and he has spent a lot of time thinking about traveling to and living on Mars. So after my previous video that discussed the dangers of going to Mars, Andy joins me to discuss the ideas that could make living there possible.
Precise measurements of Cassini’s final trajectory have now allowed scientists to make the first accurate estimate of the amount of material in the planet’s rings, weighing them based on the strength of their gravitational pull.
That estimate about 40 percent of the mass of Saturn’s moon Mimas, which itself is 2,000 times smaller than Earth’s moon tells them that the rings are relatively recent, having originated less than 100 million years ago and perhaps as recently as 10 million years ago.
Their young age puts to rest a long-running argument among planetary scientists.
Some thought that the rings formed along with the planet 4.5 billion years ago from icy debris remaining in orbit after the formation of the solar system.
Others thought the rings were very young and that Saturn had, at some point, captured an object from the Kuiper belt or a comet and gradually reduced it to orbiting rubble.
The new mass estimate is based on a measurement of how much the flight path of Cassini was deflected by the gravity of the rings when the spacecraft flew between the planet and the rings on its final set of orbits in September 2017.
Initially, however, the deflection did not match predictions based on models of the planet and rings.
Only when the team accounted for very deep flowing winds in atmosphere on Saturn, something impossible to observe from space, did the measurements make sense, allowing them to calculate the mass of the rings.
They also calculated that the surface clouds at Saturn’s equator rotate 4 percent faster than the layer 9,000 kilometers (about 6,000 miles) deep.
That deeper layer takes 9 minutes longer to rotate than do the cloud tops at the equator, which go around the planet once every 10 hours, 33 minutes.
Militzer also was able to calculate that the rocky core of the planet must be between 15 and 18 times the mass of Earth, which is similar to earlier estimates.
The team, led by Luciano Iess at the Sapienza University of Rome, Italy, reported their results today in the journal Science.
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This photograph is now half a century old. It was taken by the astronaut Bill Anders on Christmas Eve 1968 as the Apollo 8 spacecraft rounded the dark side of the moon for a fourth time.
When Earth came up over the horizon, Anders scrabbled for his Hasselblad camera and started clicking.
In that pre-digital age, five days passed. The astronauts returned to Earth; the film was retrieved and developed.
In its new year edition, Life magazine printed the photo on a double-page spread alongside a poem by US poet laureate James Dickey: “And behold / The blue planet steeped in its dream / Of reality, its calculated vision shaking with the only love.”
This was not quite the first look at our world from space. Lunar probes had sent back crudely scanned images of a crescent Earth shrouded in cloud.
A satellite had even taken a colour photo that, in the autumn of 1968, the radical entrepreneur Stewart Brand put on the cover of his first Whole Earth Catalog.
The next edition, in spring 1969, used Anders’s photograph, by now known as Earthrise.
Brand’s catalogue was a DIY manual for the Californian counterculture, a crowdsourced compendium of life hacks about backpacking, home weaving, tantra art and goat husbandry.
Its one-world, eco ethos was a weird offshoot of the macho tech of the space age – those hunks of aluminium run on rocket fuel and cold war rivalries.
But then looking back at Earth was itself a weird offshoot of the moon missions.
It just happened that Apollo 8’s aim – to locate the best lunar landing sites – needed high-res photography, which was also good for taking pictures of planets a quarter of a million miles away.
The Earth pictured in Earthrise looks unlike traditional cartographic globes that mark out land and sea along lines of latitude and longitude.
Slightly more than half the planet is illuminated. The line dividing night and day severs Africa. Earth looks as if it is floating alone in the eternal night of space, each part awaiting its share of the life-giving light of the sun.
Apart from a small brown patch of equatorial Africa, the planet is blue and white. At first glance it seems to have the sheen of blue-veined marble.
But look closer and that spherical perfection softens a little. Earth divulges its true state as oceanic and atmospheric, warmly welcoming and achingly vulnerable.
The blue is light scattered by the sea and sky. The white is the gaseous veneer that coats our planet and lets us live.
You can just make out the “beautiful blue halo”, with its gentle shift from tender blue to purple black, that Yuri Gagarin noticed on his first low-orbit flight.
That halo is our fragile biosphere, and is all that stands between us and the suffocating void.
Still, Earthrise must have changed something. What’s seen can’t be unseen. Perhaps it flits across your mind when you open Google Earth and see that familiar virtual globe gently spinning.
Just before you click and drag to fly yourself to some portion of the world no bigger than an allotment, you may briefly take in, with a little stomach lurch, that this slowly revolving sphere holds close to 8 billion people, living out lives as small and short and yet meaningful as the universe is infinite and eternal and yet meaningless.
On that gigantic, glistening marble, mottled with blue-white swirls, lies everyone.
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Night by night, star by star, astronomers are edging ever closer to learning just how crowded our universe really is—or at least our galaxy, anyway.
A quarter century after the first exoplanets were found orbiting other stars, statistics from the thousands now known have revealed that, on average, each and every stellar denizen of the Milky Way must be accompanied by at least one world.
Look long and hard enough for a planet around any given star in our galaxy and you are practically guaranteed to find something sooner or later.
But even a crowded universe can be a lonely place. Our planet-rich Milky Way may prove to be life-poor. Of all the galaxy’s known worlds, only a figurative handful resemble Earth in size and orbit.
Each occupying a nebulous “Goldilocks” region of just-rightness—a fairy-tale-simple ideal in which a world is neither too big nor too small, neither too hot nor too cold, to sustain liquid water and life on its surface.
Instead, most of the Milky Way’s planets are worlds theorists failed to predict and have yet to fit comfortably in any conception of habitability: “super-Earths” bigger than our familiar planet but smaller than Neptune.
No super-Earths twirl around our sun for solar system–bound scientists to directly study, making it that much harder to know whether any elsewhere are Goldilocks worlds—or, for that matter, whether any one-size-fits-all metric of habitability is hopelessly naive.
“If you live in a city of millions of people, you are not interested in meeting every one of them—but maybe you want to meet your immediate neighbors,” says lead author Ignasi Ribas, an astronomer at the Institute of Space Studies of Catalonia in Spain.
“This is what we are doing for the planetary systems of the stars that surround us. Otherwise we cannot answer the big questions. How does our solar system and our Earth fit in with the rest of the galaxy?
“Are there other habitable or inhabited planets? Barnard’s Star b is not giving us those answers just yet, but it is telling us part of the story we need to know.”
Located in the constellation of Ophiuchus, Barnard’s Star is so dim in visible light that it cannot be seen with unaided eyes.
Yet it has been a favorite of astronomers since 1916, when measurements revealed its apparent motion across the sky was greater than that of any other star relative to our sun.
A sign of its extremely close cosmic proximity. The star’s nearness to us is only temporary—within tens of thousands of years, its trajectory will have swept it out of our solar system’s list of top five closest stars.
According to Ribas and his colleagues, the candidate planet is at least three times heavier than our own, and circles its star in a 233-day orbit.
That would put it in the torrid orbital vicinity of Venus around our yellow sun, but Barnard’s Star is a comparatively pint-size and dim red dwarf star.
This means its newfound companion is near the “snow line,” the boundary beyond which water almost exclusively exists as frozen ice—a region around other stars thought to be chock-full of planets, but that astronomers have only just begun to probe for small worlds.
Alternatively, the planet might be covered by a thick, insulating blanket of hydrogen leftover from its birth in a spinning disk of gas and dust around its star.
Although hydrogen on smaller, hotter worlds would dissipate into space, super-Earths in frigid orbits might manage to hang on to enough of the gas to build up a massive planet-warming greenhouse effect—a possibility that throws Earth-centric Goldilocks ideas into tumult.
If this mechanism operates on Barnard’s Star b or other cold super-Earths, “our dreams that every star may have a habitable planet could well come true,” says Sara Seager, a planet-hunting astrophysicist at Massachusetts Institute of Technology who was not involved with Ribas’s study.
“There are some crazy worlds out there.”
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Astronomers have discovered a planet about the size of Earth, orbiting its star in the zone where oceans of liquid water would be possible.
A study of the newly-found planet indicates it could have an Earth-like atmosphere and water at its surface. The planet Kepler-186f is the fifth planet of the star Kepler-186, 490 light-years away.
The planet has 1.11 times the Earth’s mass. Its radius is 1.1 times that of Earth. Kepler-186f orbits at 32.5 million miles (52.4 million kilometers) from its parent star. Its year is 130 Earth days.
The planet orbits Kepler-186, an M-type dwarf star less than half as massive as the sun.
Because the star is cooler than the sun, the planet receives solar energy less intense than that received by Mars in our solar system, despite the fact that Kepler-186f orbits much closer to its star.
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Liquid water may still flow on Mars, but that doesn’t mean it’s easy to spot. The search for water on the Red Planet has taken more than 15 years to turn up definitive signs that liquid flows on the surface today.
In the past, however, rivers and oceans may have covered the land. Where did all of the liquid water go?
Why? How much of it still remains?
Liquid water appears to flow from some steep, relatively warm slopes on the Martian surface.
Features known as recurring slope lineae (RSL) were first identified in 2011in images taken by the High Resolution Imaging Science Experiment (HiRISE) camera aboard the Mars Reconnaissance Orbiter (MRO).
The dark streaks, which appear seasonally, were confirmed to be signs of salty water running on the surface of the planet.
“If this is correct, then RSL on Mars may represent the surface expression of a far more significant ongoing drainage system on steep slopes in the mid-latitudes,” a research team member said.
In 2015, spectral analysis of RSL led scientists to conclude they are caused by salty liquid water.
When Mariner 9 became the first craft to orbit another planet in 1971, the photographs it returned of dry river beds and canyons seemed to indicate that water had once existed on the Martian surface.
Images from the Viking orbiters only strengthened the idea that many of the landforms may have been created by running water.
Data from the Viking landers pointed to the presence of water beneath the surface, but the experiments were deemed inconclusive.
The early ’90s kicked off a slew of Mars missions. Scientists were flooded with a wealth of information about Mars.
Three NASA orbiters and one sent by the European Space Agency studied the planet from above, mapping the surface and analyzing the minerals below.
Some detected the presence of minerals, indicating the presence of water. Other data measured enough subsurface ice to fill Lake Michigan twice.
They found evidence for the presence of hot springs on the surface and sustained precipitation at some areas. And they found patches of ice within some of the deeper craters.
Impact craters offer a view of the interior of the red planet.
Using the ESA’s Mars Express and NASA’s Mars Reconnaissance Orbiter, scientists were able to study rocks ejected from the planet’s interior, finding minerals that suggested the presence of water.
Curiosity has found yet more evidence of water flowing on ancient Mars.
The 1-ton rover rolled through an ancient stream bed shortly after touching down in August 2012, and it has examined a number of rocks that were exposed to liquid water billions of years ago.
Mars missions aren’t the only way to search for water on Mars. Scientists studying rocks ejected from the Red Planet found signs that water lay beneath the surface in the past.
“While robotic missions to Mars continue to shed light on the planet’s history, the only samples from Mars available for study on Earth are Martian meteorites,” lead author Lauren White, of the JPL, said in a statement.
“On Earth, we can utilize multiple analytical techniques to take a more in-depth look at meteorites and shed light on the history of Mars.”
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There’s a group of people who’ve lost trust in scientists, professors, academics, and pretty much anyone who is paid to establish and dispense facts.
Some of these people are rejecting a fact established hundreds of years ago that sits at the core of most modern biology, geology and astronomy: We live on a big, round, spinning ball.
When a ship sails off toward the horizon, it doesn’t just get smaller and smaller until it’s not visible anymore. Instead, the hull seems to sink below the horizon first, then the mast.
When ships return from sea, the sequence is reversed: First the mast, then the hull, seem to rise over the horizon.
The ship-and-horizon observation is so self-evident that 1881’s “Zetetic Astronomy,” the first modern flat-Earth text, devotes a chapter to “debunking” it.
The explanation relies on assuming that the sequential disappearance is simply an illusion brought on by perspective.
This debunking does not make much sense, however, as there’s nothing about perspective that should make the bottom of an object disappear before the top.
If you’d like to prove to yourself that perspective isn’t the reason for boats disappearing hull-first and returning mast-first, bring a telescope or binoculars on your trip to the harbor.
Even with vision enhancement, the ship will still dip below the curve of the Earth.
Greek philosopher Aristotle figured out this one in 350 B.C., and nothing’s changed. Different constellations are visible from different latitudes.
Probably the two most striking examples are the Big Dipper and the Southern Cross. The Big Dipper, a set of seven stars that looks like a ladle, is always visible at latitudes of 41 degrees North or higher.
Below 25 degrees South, you can’t see it at all. And in northern Australia, just north of that latitude, the Big Dipper just barely squeaks above the horizon.
Aristotle also bolstered his belief in a round Earth with the observation that during lunar eclipses, the Earth’s shadow on the face of the sun is curved.
Since this curved shape exists during all lunar eclipses, despite the fact that Earth is rotating, Aristotle correctly intuited from this curved shadow that the Earth is curvy all around — in other words, a sphere.
This is another one of those self-evident things: You can see farther if you go higher. If the Earth was flat, you’d be able to see the same distance no matter your elevation.
Think about it: Your eye can detect a bright object, like the Andromeda galaxy, from 2.6 million light-years away.
Seeing the lights of, say, Miami from New York City (a distance of a mere 1,094 miles or 1,760 kilometers) on a clear evening should be child’s play.
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It may be the largest object in the asteroid belt that sits beyond Mars, but the dwarf planet Ceres has been surprising scientists ever since it was discovered.
The latest findings suggests that water – one of the key ingredients for life – is present across the entire surface of the rocky planetoid.
What’s more, the distribution of these icy patches suggests the dwarf is still evolving suggesting it may have its own water cycle beneath the surface.
Ceres is of particular interest to scientists because it is the closest dwarf planet to Earth and may play host to the building blocks needed for alien life.
NASA’s Dawn probe has been mapping the object since 2015 and, in a new study, experts used images captured by the craft to study chemicals on Ceres’ surface.
Specifically it looked at carbonates, compounds that have previously been detected by Dawn, which are thought to be strong indicators of liquid water.
Researchers at Italy’s Institute of Astrophysics and Space Planetology in Rome used the probe’s visible-infrared mapping spectrometer to anaylse the planet.
They found that sodium carbonates, salts of carbonic acid, can be found across the entire observed surface of Ceres. The camera reads the chemical spectrum of compounds found far below the planet’s exterior to identify them.
Some carbonate patches, which are as long as a kilometre-wide (0.6 miles), featured sodium carbonate in its hydrated form.
This could only occur around liquid water, suggesting the dwarf planet has a subsurface ocean.
The Italian team, led by Dr Filippo Carrozzo, wrote in their paper: “Hydrated sodium carbonates could form early in a global ocean in equilibrium with the altered rocky phase and be incorporated in Ceres’ crust upon freezing of that ocean.”
The chemicals could have formed as recently as a few million years ago, the researchers said.
Because they haven’t yet dehydrated, scientists suggest the planet must still be spewing water from its surface and hence is still evolving.
Patches of hydrated sodium carbonate were found by the team around craters with domes or mounds.
Some craters showed unique characteristics, such as floor fractures, that the authors say indicate areas where water had been ejected.
The researchers also focused on patches of ice covering the walls of Ceres’s Jugling impact crater.
The crater, found on Ceres’s southern hemisphere, is shadowy, dark and unlike other northern hemisphere craters where water ice has previously been found.
To better understand Juling’s water ice features, the Italian team analysed light spectrum data previously obtained by the Dawn mission.
Specifically, they compared how the amount of ice on the crater’s walls has changed over time as the sun shone on different regions.
Their results showed a clear increase of the area covered by the crater’s ice-rich wall as time progressed.
According to the authors, the trend between ice abundance and solar flux suggests that seasonal cycles of water are responsible for the observed increase.
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Most of the human population is pretty sure the Earth is round.
Neil deGrasse Tyson doesn’t have to take to Twitter to confirm it, because every kind of investigation that we can do shows that the blue marble we live on is indeed marble-shaped.
Here are 5 ways we know the Earth is round, and some you can prove yourself!
While flat-earthers will contend that there is no such thing as gravity, this force unites the entire universe. It’s everything from what makes the numbers jump on a bathroom scale to the reason why planets and stars form.
It uniformly pulls everyone on the surface of Earth toward our planet’s center of mass. That’s why you’ll weigh the same in Los Angeles as you will in Jakarta.
If the Earth was flat, gravity would no longer pull everyone the same way.
If the flat Earth would be something like a disk, those at the edge of the disk would be pulled relatively sideways, while those at the center of the plate would be pulled straight down.
The difference would change your weight enough to confuse a bathroom scale. Considering that humans have been to every landmass on Earth without celebrating sudden lightness, we can rule out a flat planet.
Day 302. #Blizzard2016 gave us an impressive view below. Stay warm! #GoodNight from @space_station! #YearInSpace pic.twitter.com/ioNOqdYDCP
— Scott Kelly (@StationCDRKelly) January 24, 2016
Where is the edge of the world according to flat-earthers? The answer changes, but it usually involves some impenetrable barrier at said edge that prevents people from going past or falling off.
Global conspiracies apparently prevent people from investigating these boundaries.
Where is the edge of the world according to flat-earthers? The answer changes, but it usually involves some impenetrable barrier at said edge that prevents people from going past or falling off.
Global conspiracies apparently prevent people from investigating these boundaries.
Hit up a friend in Australia and ask them what constellations they can see at night. Now tell them which ones pepper your patch of darkness.
They won’t be the same. Because the Earth is a shape other than a flat disk, when looking into the night sky the Earth itself can block your view.
If the flat Earth theory were true, everyone should be able to see the same constellations all the time, as if we all were staring up from the same section of summer grass.
This is “Earthrise,” arguably the most famous photo ever taken. It was beamed back to us by the astronauts on the Apollo 8 mission on Christmas Eve, 1968.
It shows the Earth as a perfect (from that vantage point at least) azure orb speckled with land and clouds, and us.
It’s true that the Earth could be a disk in this photo, and the astronauts were seeing it face-on, making it appear spherical.
To make the seasons work with a flat Earth, advocates claim that the Sun orbits in a circle above our disk, like a tetherball on an invisible string.
But timezones exist. Try calling someone in China right now and convincing them that you are experiencing the same time of day (and then apologize).
A flat Earth can’t account for how some parts of the planet are provably in darkness while other parts are bathed in light.
the Earth is not flat. From what we know of the universe, it can’t be. A conspiracy could never be big enough to deny us our planet’s true shape.
We live on a pale blue dot, believe it or not. A dot from every angle makes a sphere, who you been listening to, this is what you should hear.
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MRO captured a look at the features with the Context camera and its HiRISE instrument, revealing greater detail.
Each cell is about 5-10 kilometers (3-6 miles), with rippling sand that suggests the region may have been subjected to wind erosion.
But, there may be other processes shaping the land as well.
Exposures of bedrock seen within the cells resemble features formed as dykes, NASA explains.
These are typically associated with volcanic activity.
According to NASA, “the lack of impact craters suggest that the landscape, along with these features, have been recently reshaped by a process, or number of processes that may even be active today.
“Scientists have been debating how these honeycombed features are created, theorized from glacial events, lake formation, volcanic activity, and tectonic activity, to wind erosion.”
Recently, the Mars Reconnaissance Orbiter spotted a potential sand-producing region that could be feeding the red planet’s stunning expanse of dunes.
In a breathtaking new image, the space agency revealed a look at the sloping sediments near the boundary of Mars’ Southern highlands and Northern lowlands.
The image shows dark material is being eroded from layers of the bedrock in a massive surface depression, indicating the sand grains were not carried there by wind, according to NASA.
The image, captured by MRO’s Context Camera, shows linear markings in the huge depression that appear to slope downward.
This helps to tell the story of the processes taking place at the surface.
“The grains of sand that make up sand dunes on Earth and Mars have a hazardous existence because of the way that they travel,” NASA explained.
“Wind-blown sand is lifted above the surface of each planet before crashing onto the ground and bouncing in a sequence of repeated hops, a process called saltation.
“Sand grains can also roll along the ground as they are blown by the wind, and they are also jostled by other sand grains that are similarly flying across the surface.”
As these impacts repeat, the sand grains are worn down and smoothed out, eventually forming their spherical shape.
And, the tiny fragments that break of add to Mars’ dust deposits.
Over time, this process destroys the grains entirely – but, the region spotted in the image may help to keep Mars’ dunes going.
As Martian winter gives way to spring, the snow-covered features on the red planet begin to change form, driven by an influx of sunlight.
It might sound familiar to the seasonal changes that take place here on Earth – but, in Mars’ northern hemisphere, the snow and ice speckling the landscape is made not of water, but carbon dioxide.
And, when this ‘dry ice’ is exposed to the sun, it creates remarkable patterns across the surface.
A recent captured by NASA’s Mars Reconnaissance Orbiter has revealed a look at these features, showing how ice, sand, and gases react to form wave-like designs that ripple across the dunes.
The image was captured on May 21, 2017 by the Mars Reconnaissance Orbiter’s High Resolution Imaging Science Experiment (HiRISE) camera, according to NASA.
At this time, spring was underway in the Northern hemisphere.
The Martian surface is covered in all sorts of remarkable features that have been brought to light by the spacecraft over recent years.
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