‘Oumuamua – Close, but no cigar


The news is full of images of a mysterious cigar shaped object from another star system. The information is minimal; just enough to hint that this could be some kind of alien spacecraft. It is cylindrical, we’re told, rotating and may be composed of metal. Fantastic! So is this it?

My first reaction was to go straight to the NASA website to get the hard facts but I was disappointed to find that the last reference to ‘Oumuamua was back in November and the page no longer exists. Forty years ago I would have considered this material for a good old conspiracy theory especially when, on Monday, The Independent reported “Nasa to hold major announcement after artificial intelligence makes planet-hunting breakthrough

Few things are certain in this world but one is that the media will sensationalise any story with a hint of the extraterritorial. However, equally certain is that, when one day, the first alien craft is detected, Professor Brian Cox and legions of his boring, stable, “know it all” colleagues will be on the telly scoffing at the speculation and claiming that this is probably just another asteroid (albeit with the words Red Dwarf painted across the side).

So, at the moment, nobody knows and maybe there’s still a chance for something fantastic? It’s fun to speculate.

But how do we find out what in blue blazes is going on? Wikipedia saves the day. The Wikipedia entry is fairly extensive though dreadfully technical and dreary so I have taken the liberty of précising it here. Though we should not give up hope just yet, it does sound as if the information in the mainstream media is over stated. The cigar shape and its rotation are not known through observation but inferred from its variable luminosity. The widely distributed image of ʻOumuamua is an artist’s impression and very little is known of its actual appearance.

Possible origin
Possible origin

Wikipedia tells us this; ‘Oumuamua is the first known interstellar object to pass through the Solar System. It was discovered on 19 October 2017 using a facility known as Pan-STARRS which consists of two 1.8 m telescopes located linked to a computing facility that continually surveys the sky for moving or variable objects. It was discovered 40 days after its closest approach to the Sun at about 33,000,000 km from Earth (about 85 times as far away as the Moon). It is moving so fast relative to the Sun that there is no chance it originated in the Solar System and it will not be captured into orbit and so will eventually leave the Solar System.

Its origin are unknown but its trajectory makes it appear to have come from roughly the direction of the star Vega in the constellation Lyra (not to be confused with the pop star Suzanne Vega who lives in the USA). It is heading away from the Sun, towards Pegasus. It would have taken ʻOumuamua 600,000 years to reach the Solar System from Vega but Vega was not in the same part of the sky back then. It has been speculated that the object may have been ejected from a stellar system in the Carina Nebula some 45 million years ago.

It entered the solar system from above, what is known as, the ecliptic which is the plane that most of the planets orbit around so it could not have had an encounter with any of the Sun’s planets. It is highly elongated and shows no sign of the gaseous envelope, known as a coma, formed when a comet passes close to the Sun . So it’s not a comet. It may be composed of dense metal-rich rock that has been reddened by millions of years of exposure to cosmic rays. According to one hypothesis, ʻOumuamua could be a fragment from a tidally disrupted planet.

So, just another lifeless lump of rock then?

Well, don’t be too despondent. Many of these assertions are inferences from fairly minimal observations. We don’t actually know that before it was detected it hadn’t been maneuvering all over the place and, as yet, there are no images of it other than vague dots. Though examination by SETI‘s radio telescope detected no unusual radio emissions more detailed observations are planned and others are speculating about sending a probe. ʻOumuamua is moving too fast for any existing craft to catch it but the Initiative for Interstellar Studies (i4is) thinks there may be several options for sending a spacecraft within 5 to 10 years by using slingshot effects encountered when approaching other planets or the sun.

One thing I believe this story has done for us is to make us pay attention. We tend to think that when First Contact occurs then the first we know about it will be when a flying saucer lands on the White House lawn. In fact, most probably, the first we’ll know about it will be a report such as this.

The Wikipedia entry ends with the statement that astronomers estimate that interstellar objects similar to ʻOumuamua pass inside the orbit of Earth several times per year which, if true, makes you wonder why the bloody hell nobody thought to look at one before.


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