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Ian Hitchcock/Getty Images
Ian Hitchcock/Getty Images

Can’t See the Eclipse in Person? Watch NASA’s 360° Live Stream

Ian Hitchcock/Getty Images
Ian Hitchcock/Getty Images

Depending on where you live, the historic eclipse on August 21 might not look all that impressive from your vantage point. You may be far away from the path of totality, or stuck with heartbreakingly cloudy weather. Maybe you forgot to get your eclipse glasses before they sold out, or can't get away from your desk in the middle of the day.

But fear not. NASA has you covered. The space agency is live streaming a spectacular 4K-resolution 360° live video of the celestial phenomenon on Facebook. The livestream started at 12 p.m. Eastern Time and includes commentary from NASA experts based in South Carolina. It will run until about 4:15 ET.

You can watch it below, on NASA's Facebook page, or on the Facebook video app.

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Big Questions
Does Einstein's Theory of Relativity Imply That Interstellar Space Travel is Impossible?
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Does Einstein's theory of relativity imply that interstellar space travel is impossible?

Paul Mainwood:

The opposite. It makes interstellar travel possible—or at least possible within human lifetimes.

The reason is acceleration. Humans are fairly puny creatures, and we can’t stand much acceleration. Impose much more than 1 g of acceleration onto a human for an extended period of time, and we will experience all kinds of health problems. (Impose much more than 10 g and these health problems will include immediate unconsciousness and a rapid death.)

To travel anywhere significant, we need to accelerate up to your travel speed, and then decelerate again at the other end. If we’re limited to, say, 1.5 g for extended periods, then in a non-relativistic, Newtonian world, this gives us a major problem: Everyone’s going to die before we get there. The only way of getting the time down is to apply stronger accelerations, so we need to send robots, or at least something much tougher than we delicate bags of mostly water.

But relativity helps a lot. As soon as we get anywhere near the speed of light, then the local time on the spaceship dilates, and we can get to places in much less (spaceship) time than it would take in a Newtonian universe. (Or, looking at it from the point of view of someone on the spaceship: they will see the distances contract as they accelerate up to near light-speed—the effect is the same, they will get there quicker.)

Here’s a quick table I knocked together on the assumption that we can’t accelerate any faster than 1.5 g. We accelerate up at that rate for half the journey, and then decelerate at the same rate in the second half to stop just beside wherever we are visiting.

You can see that to get to destinations much beyond 50 light years away, we are receiving massive advantages from relativity. And beyond 1000 light years, it’s only thanks to relativistic effects that we’re getting there within a human lifetime.

Indeed, if we continue the table, we’ll find that we can get across the entire visible universe (47 billion light-years or so) within a human lifetime (28 years or so) by exploiting relativistic effects.

So, by using relativity, it seems we can get anywhere we like!

Well ... not quite.

Two problems.

First, the effect is only available to the travelers. The Earth times will be much much longer. (Rough rule to obtain the Earth-time for a return journey [is to] double the number of light years in the table and add 0.25 to get the time in years). So if they return, they will find many thousand years have elapsed on earth: their families will live and die without them. So, even we did send explorers, we on Earth would never find out what they had discovered. Though perhaps for some explorers, even this would be a positive: “Take a trip to Betelgeuse! For only an 18 year round-trip, you get an interstellar adventure and a bonus: time-travel to 1300 years in the Earth’s future!”

Second, a more immediate and practical problem: The amount of energy it takes to accelerate something up to the relativistic speeds we are using here is—quite literally—astronomical. Taking the journey to the Crab Nebula as an example, we’d need to provide about 7 x 1020 J of kinetic energy per kilogram of spaceship to get up to the top speed we’re using.

That is a lot. But it’s available: the Sun puts out 3X1026 W, so in theory, you’d only need a few seconds of Solar output (plus a Dyson Sphere) to collect enough energy to get a reasonably sized ship up to that speed. This also assumes you can transfer this energy to the ship without increasing its mass: e.g., via a laser anchored to a large planet or star; if our ship needs to carry its chemical or matter/anti-matter fuel and accelerate that too, then you run into the “tyranny of the rocket equation” and we’re lost. Many orders of magnitude more fuel will be needed.

But I’m just going to airily treat all that as an engineering issue (albeit one far beyond anything we can attack with currently imaginable technology). Assuming we can get our spaceships up to those speeds, we can see how relativity helps interstellar travel. Counter-intuitive, but true.

This post originally appeared on Quora. Click here to view.

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Space
Astronauts on the ISS to Teach Christa McAuliffe's Lost Science Lessons
NASA
NASA

Christa McAuliffe was set to become the first private citizen to travel to space when she boarded the Challenger space shuttle on January 28, 1986. That dream was cut tragically short when the shuttle exploded 73 seconds after liftoff, killing all seven passengers onboard. Now, 32 years later, part of McAuliffe's mission will finally be realized. As SFGate reports, two NASA astronauts are teaching her lost science lessons in space.

Before she was selected to join the Challenger crew, McAuliffe taught social studies at a Concord, New Hampshire high school. Her astronaut status was awarded as part of NASA's Teacher in Space Project, a program designed to inspire student interest in math, science, and space exploration. McAuliffe was chosen out of an applicant pool of more than 11,000.

Once in orbit, McAuliffe had planned to conduct live and taped lessons in microgravity for her students and the world to see. Though that never happened, she left behind enough notes and practice videos for astronauts to carry through with her legacy 32 years later. On Friday, January 19, astronaut Joe Acaba announced that he and his colleague Ricky Arnold will be sharing her lessons from the International Space Station over the upcoming months. The news was shared during a TV linkup with students at Framingham State University where McAuliffe studied.

McAuliffe's lost lesson plan includes experiments with Newton's laws of motion, bubbles, chromatography, and liquids in space, all of which will be recorded by Acaba and Arnold and shared online through the Challenger Center, a nonprofit promoting space science education.

It will be the first time students will get to see the lessons performed in space, but it won't be the only footage of the lessons available on the internet. Before the doomed Challenger flight, McAuliffe was able to practice her experiments in NASA's famous Vomit Comet. You can watch one of her demonstrations below.

[h/t SFGate]

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