{"id":10200,"date":"2016-09-06T22:59:54","date_gmt":"2016-09-06T14:59:54","guid":{"rendered":"http:\/\/stuif.com\/blog\/?p=10200"},"modified":"2016-09-06T23:06:56","modified_gmt":"2016-09-06T15:06:56","slug":"our-nearest-neighbour","status":"publish","type":"post","link":"https:\/\/stuif.com\/blog\/?p=10200","title":{"rendered":"Our nearest neighbour?"},"content":{"rendered":"

As you may know from my \u00a0blog,\u00a0I think we may be alone in the\u00a0Universe<\/a>. But of course I would be more than happy if (intelligent) life would be found outside our own planet. My PC is taking part in the SETI project, see my blog \u00a0Anybody out there?<\/a>\u00a0Last week there was excitement about a\u00a0strong signal from a sunlike star, but: No alien signal, says SETI astronomer<\/a>.<\/p>\n

Numerous extrasolar planets have been found by now, as of 1 September 2016 the count was 3518<\/a>. A few dozen of them might be able to support life (rocky, similar size to Earth, orbiting in the habitable zone<\/a> of their star).<\/p>\n

So, why did this Letter to Nature (one of the leading science magazines) : \u00a0A terrestrial planet candidate in a temperate orbit around Proxima Centauri<\/a> cause so much commotion that it became front page news in the media?<\/p>\n

The answer is simple: Proxima Centauri is not just one of the\u00a0hundreds of billion stars in our galaxy. It is the star closest to our Sun<\/span>, at a distance of 4.22 lightyear “only<\/span>“,<\/p>\n

Let’s have a closer look at this nearest neighbour of the Sun. \u00a0Where can we find it in the night sky? And can we see it \u00a0with unaided eyes or binoculars?<\/p>\n

Here is the night sky (in Malaysia) in March, south-eastern direction. You will notice three constellations,\u00a0dominated by Centaurus. The name comes from\u00a0Greek mythology, where a Centaur<\/a> is a half-horse half-man creature\"Sky-march\"<\/a><\/p>\n

\"centaurus_contellation\"<\/a><\/p>\n

Here is how the Greek saw a Centaur in the stars.<\/p>\n

You may find it difficult to see a centaur, but the two bright stars in his left leg are conspicuous. Rigel Kent, better known as \u03b1 Centauri, is the third-brightest star in the sky, after Sirius and \u00a0Canopus.\u00a0<\/span><\/p>\n

Hadar (\u03b2 Centauri) is also a bright star.<\/span><\/p>\n

\u03b1 Centauri is actually a star system<\/a>, consisting of three stars.\u00a0Two of them, \u03b1 Centauri A and B are so close that they can not be separated by the unaided eye. Here is an image taken by the Hubble telescope.<\/p>\n

\"Best<\/a><\/p>\n

 <\/p>\n

\u03b1 Centauri A\u00a0(to the left) is slightly larger than the Sun, while B\u00a0is a bit smaller. They orbit around each other with a period of 80 years.<\/p>\n

 <\/p>\n

 <\/p>\n

The third component, \u03b1 Centauri C is a red dwarf<\/a>, much smaller and cooler (more reddish) \u00a0than the Sun. Very far away \u00a0(about 0.21 ly) from the other two. If it is bound by gravitation to A and B (not 100% sure), the estimated orbiting period is ~ 500.000 year. Here are A and B (seen as one star here) and C (in the center of the red circle). The other stars are Milky Way stars, much farther away.<\/p>\n

\"\"<\/a><\/p>\n

The \u03b1 Centauri system is closer to the Sun than any other star, about 4.35 ly\u00a0away,\u00a0and of the three components, \u03b1\u00a0Centauri C is a bit closer (4.22 ly) and therefore\u00a0it has been named Proxima Centauri.<\/p>\n

Because of the close distance, the system has been studied intensively. A\u00a0planet might be orbiting\u00a0\u03b1 Centauri\u00a0B,<\/a> but even if found to be true,\u00a0it will not be habitable.<\/p>\n

 <\/p>\n

Now a planet has been found, orbiting the red dwarf in the\u00a0\u03b1 Centauri system. It has been called Proxima b<\/a>. Very close to the\u00a0star, orbiting it in about 11 days only. Compare this with Mercury’s period of 88 days. But because the star is less bright than the Sun, the planet is still in the habitable zone. Here is an artist impression how the planet could look like.\u00a0\u03b1 Centauri A and B are also shown, as bright stars.<\/p>\n

\"Artist's_impression_of_the_planet_orbiting_Proxima_Centauri-002\"<\/a><\/p>\n

Our closest neighbour! But a distance of 4.22 light-year means that Proxima b\u00a0is still 40 trillion\u00a0km away from Earth. At this moment spacecraft New Horizon<\/a>, after taking spectacular pictures of dwarf planet Pluto, is leaving our solar system with a respectable speed of ~ 60.000 km\/h. That is fast, but it would take ~ 80.000 year to reach Proxima b.<\/p>\n

Here is what the Mail Online reported on 24\/8. “The second Earth that we could visit in our lifetime<\/span>” \u00a0and \u00a0“just four light years away<\/span>”<\/p>\n

\"\"<\/a><\/p>\n

Actually there is an audacious plan to send a probe to Proxima b. Not a spaceship but a space-chip<\/span>! Not one probe, but a swarm of them. Interested? \u00a0The project\u00a0is called .Breakthrough Starshot<\/a>\u00a0and it deserves a separate blog post.<\/p>\n

Here only a few comments on the idea of a “second Earth”.<\/p>\n