Home Sweet Home

The search for home. Published by Grafton Books 1987. Cover illustration by Tim White.

All animals need a sense of where home is.  It’s essential for survival to know where you can go to stand a better chance of being safe and amongst friends.  Humans are no different, but as our technological civilization has expanded, our idea of what comprises “home” has changed.

This may be increasingly uncertain for any future galactic culture.  In his 1986 science fiction novel Foundation and Earth, the last chronologically in the Foundation series, Isaac Asimov describes a distant future where humanity has spread throughout the Galaxy, but there is a need to find the (by then) legendary planet where the human race originated.  The home planet is expected to offer the answers to certain questions which must be resolved if the direction of humanity’s future in the Galaxy is to be assured, but the underlying thought is that the race has lost touch with its roots.  No-one can be sure whether Earth still exists, or ever did.  The adventures of Asimov’s characters on the planets visited during their search bind together several of the themes in his novels over the years.

We, of course, know that Earth is our home, and the only one we have.  We depend on it entirely for our existence.  In turn, the Earth’s home is with the other planets of our Solar System, orbiting our Sun.  As we adapt to a more advanced space-faring civilization, the Sun will still represent our home for at least the foreseeable future.  But where is the Sun’s home?  As we look around, it appears to be isolated in space – over four light years from the nearest other star, Alpha Centauri, and nearly nine light years from Sirius, the local big fish in our relatively small pond in the Orion Arm.

It’s now fairly well established that stars such as our Sun form in stellar “nurseries” where gravity works on dust clouds to create proto-stellar objects surrounded by huge disks which condense to form planets.  In his 2015 book Origins, the science writer Jim Baggott proposes the name ‘Neith’ for the giant molecular cloud which gave birth to the Sun and its siblings about 4.6 billion years ago, named after the Egyptian goddess who was the mother of Ra, the Sun god.  But we are no longer in or near Neith, and we see no signs of our Sun’s siblings anywhere near us now.

What may have happened is that the Sun was ejected from the nursery at an early stage, though not too violently so as to disrupt the planetary system, and it now exists as an orphan in space.  There’s an obvious danger in sounding too anthropomorphic about all this, but let’s not forget Gregory Matloff’s lecture Stellar Consciousness to the BIS in 2013, when he explained some intriguing ideas about just what might lie behind that concept.   Even so, the question is whether we can now identify where the Sun’s nursery was, and might now be.  There is a potential candidate.

The open star cluster known as Messier 67 is around 2,700 light years away, and includes over a hundred stars which are noticeably similar to the Sun.  Some are known to have their own planetary systems.  Its age could be as high as five billion years, which would fit reasonably with the Sun’s age.  Unfortunately, as Pichardo et al explain in The Sun was not born in M67 (The Astronomical Journal, March 2012), computer simulations of the motion of stars suggest that gravitational ejection would probably not have put us in our position today.  Frankly, though, there are so many complexities in the movements of the spiral arms of the Milky Way Galaxy that almost anything could have happened, and more recent studies have confirmed further Sun-like characteristics for a number of stars in the cluster.  It’s still just possible that M67 was once the stellar nursery that we seek.

So, on a clear night, you may be able to pick out M67 using binoculars or a small telescope.  Look towards the easternmost star of the upside-down Y-shape of the constellation of Cancer (the Crab), and it’s just a little to the west.  You may actually be looking at our true home.

Richard Hayes, Assistant Editor (Odyssey)

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