SkyMatters: Oumuamua is the first object ever to be observed which originated outside the solar system

By 7pm on December 25, we are all likely to have had our fill of turkey and ham, writes Niall Smith.

The thought of going outside into the cold night air might seem unpalatable, but if you can resist the temptation to lounge in the chair you will be rewarded with a view of the mightiest of all constellations, Orion (the Hunter), rising in the East.

The constellation is identified by the three stars of the Hunter’s Belt.

If you look a little below the leftmost star you will see a fuzzy patch which is in reality a stellar nursery called the Orion Nebula that is giving birth to new stars right now.

Our solar system would have looked somewhat similar about 5 billion years ago had we looked on from a distance of 1,300 light years, which is the distance to the Orion Nebula. Although close in galactic terms, 1300 light years is mind-bogglingly far away and it will be a long time before we develop the capabilities to visit such locations, should we ever choose to do so.

But sometimes our Universe brings interesting objects from afar to us and the first object to truly fit into that category was discovered on October 19, 2017.

Named Oumuamua, this cigar-shaped lump of rock must have originated around some unidentified star and ended up wandering through the galaxy for millions to billions of years. Having rounded the Sun, it is now heading back out of our solar system, never to return, a lonely wanderer in an immense cosmos.

What makes this discovery so exciting is that we can now start to analyse objects from other solar systems in some detail and compare with our own.

The results from what we have learned from Oumuamua’s brief visit is that we are more similar than different.

Earlier, in December 3, we can all enjoy a “supermoon” (the first and only one in 2017). This phenomenon occurs when the full moon coincides with the moon being at, or near its closest approach to the Earth in its orbit.

The December supermoon will see our nearest neighbour appear seven percent larger and 16% brighter. Look for the supermoon rising at about 16:40. As the moon rises you get a double benefit because of an optical illusion that already makes the Moon appear larger when it’s near the horizon.

On the night of December 13 and into the morning of December 14 keep an eye out for the Geminids Meteor Shower, which often produces 100 meteors an hour, many showing interesting colours as the tiny specks of dust from which they originate burn up in the Earth’s atmosphere. Geminids, like any meteors, are best viewed away from lights using only your eyes.

You can’t predict where or when the next meteor will occur and we used to play a game as kids to see who would see the next one – no cheating, mind! The shortest day of the year occurs on December 21 when daylight will last just seven hours, 29 minutes and 59 seconds — almost nine hours less than the year’s longest day in the summer!

While many of us are dreaming of the long summer days, take the opportunity of the early sunsets in particular, to bring the kids out to see the stars twinkle, punctuated by the slow movement of satellites as they orbit above our heads.

And soak in the beauty of our wonderful being.

Niall Smith is Head of Research at CIT and Head of Blackrock Castle Observatory


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