Planet Discovered Around Barnard's Star

[Still_Small_Voice]

I know this is old news, but I just read about it recently.

November 23rd 2018

Astronomers have found that Barnard’s star — a very close, fast-moving, and long studied red dwarf — has a super-Earth sized planet orbiting just beyond its habitable zone.

The discovery relied on data collected over many years using the tried-and-true radial velocity method, which searches for wobbles in the movement of the host star.

But this detection was something big for radial velocity astronomers because Barnard-b was among the smallest planet ever found using the technique, and it was the furthest out from its host star as well — orbiting its star every 233 days.

For more than a century, astronomers have studied Barnard’s star as the most likely place to find an extrasolar planet.

Ultimately, said Ignasi Rablis of Spain’s Institute of Space Studies of Catalonia, lead author of the paper in journal Nature, the discovery was the result of 771 observations, an extremely high number.

And now, he said, “after a very careful analysis, we are over 99 percent confident the planet is there.”

https://astrobiology.nasa.gov/news/barnards-star/

[Vort]

Wasn't Barnard's Star the setting for a Star Trek film or some other sci-fi movie?

[Carborendum]

12 minutes ago, Vort said:

Wasn't Barnard's Star the setting for a Star Trek film or some other sci-fi movie?

It was. I'm surprised you remembered such a reference.  I thought it was only hardcore Trekkers like me.

It was the setting for the Episode where everyone gets a disease where they behave like they're drunk.

[Vort]

Actually, I was thinking of Wolf 359. Oops. Never mind.

[Still_Small_Voice]

That is going to be my next vacation.  I am going to the planet that orbits Barnard's Star.  It is only about 35.271 trillion miles away from here.

[Carborendum]

1 hour ago, Vort said:

Actually, I was thinking of Wolf 359. Oops. Never mind.

Wolf 359???  That is probably the most famous location in all of Star Trek (apart from sector 001).

Wolf 359 was where the Borg war was first fought - and lost.

[Jamie123]

I can remember astronomers talking about Barnard's Star and its wobbling - and the likely presence of large planets there - from back in the 1970s.

[Still_Small_Voice]

Excuse the math if I messed up.

The distance of the Moon from the Earth is about 222,000 miles depending on where the Moon is at in its orbit.  Barnard's Star is only a little over 158,878,378 times further away than the Moon. 

The Space Shuttle travels up to about 17,500 miles per hour.  Traveling at about that speed it would only take you around 229,920 years to get to Barnard's star.

[Vort]

47 minutes ago, Still_Small_Voice said:

The Space Shuttle travels up to about 17,500 miles per hour.  Traveling at about that speed it would only take you around 229,920 years to get to Barnard's star.

Such comparisons are popular in space-news circles. I hope I'm not a party pooper for pointing out that the comparisons are actually pretty much meaningless.

The space shuttle's orbital velocity is the same as any other satellite at that orbital altitude. It's exactly fast enough to "fall around the earth", counteracting the downward force of gravity but not so much that the satellite actually gains altitude. If the space shuttle orbited at a lower altitude (but still substantially outside earth's atmosphere), it would have to go slightly faster. If it orbited at a higher altitude, it would have to go slower. That may seem paradoxical, but it's basic orbital mechanics.

The earth sits at the bottom of a fairly large gravity well, a well that the earth's mass generates. Consider it as a funnel, or perhaps a vortex 😉, surrounding the earth, with the earth at the bottom. It takes energy to lift a rocket (satellite, space shuttle, whatever) up out of that gravity well, just as it takes energy to lift a marble from the bottom of the funnel up higher. It takes more energy to make the rocket/satellite/space shuttle go around the earth at a fast enough speed that it doesn't just fall right back down, just as it takes energy to make the marble roll around the funnel with enough momentum so that it doesn't fall down to the bottom, but rolls around the funnel instead.

But the thing is this: The marble rolling around the funnel is still deep inside the funnel, just as the satellite orbiting the earth in so-called low-earth orbit (LEO) is still very near the earth, near the bottom of that gravity well. A whole lot more energy is required to get higher up the earth's gravity well. It took a rocket over 300 feet tall to store enough energy to fly the Apollo crews and their equipment to the moon (which of course has its own smaller gravity well to deal with). By the time you're high enough up the earth's gravity well to go to the moon, you're almost high enough to escape earth's gravity altogether and go into what's called interplanetary space. At that point, you're orbiting the sun at just about the same distance as the earth does. So now you're in the sun's gravity well, and if you want to go to Mars or Jupiter or any of the other outer planets, you have to supply more energy to climb out of that solar gravity well.

I believe we have three or four objects that have sufficient energy to escape the sun's gravity well: One of the Pioneer probes, the two Voyager probes, and I think that probe that flew by Pluto and Charon five or so years back. New Horizons (just Googled it). If you want to go anywhere other than neighboring stars, you will have to add more energy, perhaps enough to escape the Milky Way galaxy's gravity well.

Here is a great representation of gravity wells as I've been discussing them:

If you look closely at the lower right-hand corner of the picture, it shows LEO in relation to the surface of the earth and how much more energy you need to add to get to the moon or a higher orbit.

Anyway, the point is that to go to Barnard's Star, you'd have to have sufficient energy (i.e. speed) to escape the sun entirely. That actually has almost nothing to do with the orbital speed of a satellite in LEO. In principle, your speed to Barnard's Star could be either faster or slower than the shuttle's orbital velocity, but in actual practice it would certainly be a very great deal faster. Once you've spent the energy needed to dig yourself out of the sun's gravity well, you're going to gain velocity much faster as you expend energy.

Edited October 21, 2020 by Vort

[Still_Small_Voice]

Voyager 1 spacecraft probe is now in Instellar space from what I read.  It is about 14 billion miles away from the Earth in space now.  And 14 billion miles is not even far at all when you consider Alpha Centari A and B stars are about 4.3 light years away and the Milky Way galaxy is about 100,000 light years from one side to the other.

[Jamie123]

1 hour ago, Still_Small_Voice said:

Voyager 1 spacecraft probe is now in Instellar space from what I read.  It is about 14 billion miles away from the Earth in space now.  And 14 billion miles is not even far at all when you consider Alpha Centari A and B stars are about 4.3 light years away and the Milky Way galaxy is about 100,000 light years from one side to the other.

Space is big.

Really big. You just won't believe how vastly, hugely, mind-boggling big it is. I mean, you may think it's a long way down the road to the chemist, but that's just peanuts to space. Listen; when you're thinking big, think bigger than the biggest thing ever and then some. Much bigger than that in fact, really amazingly immense, a totally stunning size, real 'wow, that's big', time. It's just so big that by comparison, bigness itself looks really titchy. Gigantic multiplied by colossal multiplied by staggeringly huge is the sort of concept we're trying to get across here.

Edited October 22, 2020 by Jamie123