NASA finds seven earth size planets, but are they anything like Earth?

Friday, 24 February, 2017

After days of keeping us in suspense about a new discovery, NASA let the cat out of the bag, in the early hours of yesterday morning. The TRAPPIST optic robotic telescope, located in Chile, recently identified a dwarf star, about forty light years distant from Earth, that is host to seven planets around about the same size as Earth.

Come on now, you didn’t think they were going to announce that an alien civilisation had been found, did you?

This is still a significant discovery though. Particularly as three of the seven bodies orbiting TRAPPIST-1 – the star also takes its name from the Belgian operated telescope – are within its solar system’s so-called Goldilocks, or habitable zone, an area capable of supporting life, that is neither too hot, nor too cold.

It is this bit that is especially of interest, as it means these planets may habour water in liquid form, and, as a result, potentially life of some sort. And that is obviously an exciting prospect. But talk we may one day be able to emigrate there is well wide the mark, to say the least.

There is, you see, a big difference between a planet that is “earth-like”, and one exactly like Earth. Or a planet that could be called an Earth twin, or Earth analog. For example, Proxima b, an exoplanet within the habitable zone around Proxima Centauri, the nearest star to the Sun, is considered to be earth-like, as it is a rocky, or terrestrial planet.

It might have some sort of atmosphere, and possibly there could be liquid water on its surface. But Proxima b may be far from habitable, at least as far as humans are concerned. As Proxima Centauri is a red dwarf star, which are relatively cool, Proxima b would need to be quite close, to be within the habitable zone.

This sort of proximity however could mean Proxima b is tidally locked, meaning the planet’s rotational period matches the time it takes to orbit the star. This result here is only one side of the planet would ever face the star.

Therefore, the sunny side of Proxima b would be quite warm, whereas the night side would be extremely cold. The only spots that might be conducive to life, would be near the day-night terminator. In addition, the planet is also exposed to stellar wind pressures far greater than those that Earth experiences.

Not all that earth-like, after all. So while some form of life may manage to eke out an existence there, it would hardly be suitable for human occupation. The same conditions could well apply to the planets within the Goldilocks zone of TRAPPIST-1, given it to is a relatively cool dwarf star.

At the very least, they’re quite possibly tidally locked. If we’re looking for a new planet to settle on then, it needs to be an Earth twin. This is a planet, as the name suggests, that is identical in almost every way to ours. And if there are at least one hundred billion planets in our galaxy, the Milky Way, then it stands to reason some proportion must be virtually identical to Earth.

But an Earth twin candidate needs to be more than a terrestrial planet, orbiting within the habitable zone of its solar system though. In their book, Rare Earth, published in 2000, US paleontologist Peter D. Ward, and Donald Brownlee, a professor of astronomy, outlined the criteria necessary for a planet to be classified as an Earth twin:

The right distance from a star; habitat for complex life; liquid water near surface; far enough to avoid tidal lock; right mass of star with long enough lifetime and not too much ultraviolet; stable planetary orbits; right planet mass to maintain atmosphere and ocean with a solid molten core and enough heat for plate tectonics; a Jupiter-like neighbor to clear out comets and asteroids; plate tectonics to build up land mass, enhance bio-diversity, and enable a magnetic field; not too much, nor too little ocean; a large moon at the right distance to stabilize tilt; a small Mars-like neighbor as possible source to seed Earth-like planet; maintenance of adequate temperature, composition and pressure for plants and animals; a galaxy with enough heavy elements, not too small, elliptical or irregular; right position the galaxy; few giant impacts like 65 million years ago; enough carbon for life, but not enough for runaway greenhouse effect; evolution of oxygen and photosythesis; and, of course, biological evolution.

That’s an extensive list. Some astronomers think two percent of the Milky Way’s planets may be Earth twins, meaning there could be two billion such bodies. Given the exacting conditions required for their existence though, I think the actual number may be far smaller.

It could a very long time, therefore, before any announcement is made regarding the discovery of a truly earth-like planet, that is, an Earth analog. It also means we have to take greater care of our own Earth. Clearly we’re not going to be emigrating anywhere else in any hurry.

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Saturn’s rings, as seen in unprecedented detail, by Cassini–Huygens

Friday, 3 February, 2017

Saturn's rings, photo via NASA

NASA’s Cassini–Huygens automated space probe has been orbiting Saturn, the sixth planet of the solar system, since 2004. During that time it has taken countless photos, including this set, that show’s the planet’s ring system in intricate detail. Incredible. Here’s a larger version of the above photo.

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UFO, psychics, and spies. The truth is amongst the CIA’s data

Wednesday, 1 February, 2017

The truth is out there. Somewhere, surely. Dig through the twelve million, that’s right, twelve million pages of data, or some 930,000 declassified documents, that the CIA recently made searchable online, and see what you can learn about past investigations into unidentified flying objects, psychics, and spies, and the like.

A great way to spend a rainy day, maybe?

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Graffiti, on Earth, and to the outer reaches of space, by Josh Keyes

Tuesday, 24 January, 2017

Artwork by Josh Keyes

Portland based painter Josh Keyes may not be a graffiti artist, but he can imagine a world where graffiti is to be seen no matter where you look, or where you are.

The likes of whales and icebergs are fair game for this highly resourceful would-be tagger, and not even leaving the planet helps either, as this work-in-progress image of a Space Shuttle, titled “Tin Can”, shows.

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Epoch, a journey of epic proportions through the solar system

Wednesday, 18 January, 2017

Dim the lights, turn up the volume, and go into full screen mode for Epoch, a journey to the far reaches of the solar system.

By Ash Thorp, whose video NONE I linked to last October, and San Francisco based Danish art director and motion designer, Chris Bjerre.

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There’s a mere two trillion galaxies in the night sky. Possibly

Wednesday, 19 October, 2016

A paper recently published in the Astrophysical Journal suggests there may be ten times more galaxies in the universe than was thought. That would make for two trillion of them, including our family of stars, the Milky Way. Incredible.

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If you thought that living on Mars was expensive, try the Moon

Friday, 30 September, 2016

There’s been a little bit of talk in recent days about sending people to Mars.

While it’s an exciting prospect, it’s not exactly inexpensive. To get an idea of the cost, plus an outline of what else is required, which isn’t insignificant, lets dial things back, and consider establishing a four person base, for a year, on the Moon.

While it’s the sort of thing we need to consider, living elsewhere, either in the Solar System, or beyond, it’s not without its challenges. To say the least.

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If we lived on Proxima b, we’d be residing in the twilight zone

Thursday, 15 September, 2016

No, we shouldn’t get too excited by the prospect that an Earth-like exoplanet circles the star nearest to us. Earth-like it may be, but make no mistake, Centauri b, that orbits red dwarf star Proxima Centauri, is not like Earth. For one thing, the planet is so close to its host star, it is tidally locked. This means it does not rotate on its axis as Earth does.

Therefore it is perpetually day time on one side of the side of the planet, while the other hemisphere is forever cloaked in darkness. One side would be rather warm, the other quite chilly. Only the border between the two, a veritable twilight zone, might be a little Earth-like. On that basis then, it may not be too bad

There will be three different climate zones. The side always facing its star will be consistently sun-baked, receiving scorching, direct sunlight without ever getting a break from it. Similarly, the side facing away from the star will experience eternal night, and should be dark and frozen, but with spectacular views of the Universe. The border between the night and day sides – a “ring” around the planet – will experience an eternal dawn/sunset, with perhaps the most Earth-like conditions.

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If you’d spent 534 days in space, you’d return with a few photos

Friday, 9 September, 2016

Photo by Jeff Williams

US astronaut Jeff Williams has spent five hundred and thirty-four days in space, during the course of his career. That includes a one hundred and seventy-two day stint aboard the International Space Station (ISS), as part of Expedition 47/48. He had been aboard the ISS for two previous expeditions. All up, that’s quite some time to be away from Earth.

Like other ISS crew members, he found some time to take a few photos, during his last stay. Some incredible photos, I should say, that you can see on his Facebook page.

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Could there be a habitable planet orbiting Proxima Centauri?

Tuesday, 23 August, 2016

The closest star to Earth is Proxima Centauri, a red dwarf that may, or may not, be part of the Alpha Centuari binary star system. If Proxima Centauri were found to be gravitationally bound to the binary star, then Alpha Centuari would become known as a trinary, or triple, star system.

Just some trivia for you there.

Proxima Centauri, however, has been making headlines, as unconfirmed reports suggest it may host an Earth like planet, within its habitable zone, meaning the presence of life may be possible.

But in what may prove to be the most exciting find to date, the German weekly Der Spiegel announced recently that astronomers have discovered an Earth-like planet orbiting Proxima Centauri, just 4.25 light-years away. Yes, in what is an apparent trifecta, this newly-discovered exoplanet is Earth-like, orbits within its sun’s habitable zone, and is within our reach. But is this too good to be true?

As an aside. With the Sun halfway through its ten billion year lifespan, we’ll be on the look out for a new home eventually, and it’s thought that relocating to a planet orbiting a red dwarf might be a good move. Red dwarf stars live for trillions of years, so our descendants wouldn’t need to think about moving again for a long, long, time.

If a habitable planet were found to be orbiting Proxima Centauri, might it one day become our new residence?

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