Last year, scientists observed a space rock flying through the solar system. It had a length of almost a quarter-mile, and it was quite skinny. They named it `Oumuamua – which means “messenger from afar” in Hawaiian.
Analyzing its trajectory, scientists concluded that the space rock came from a distant solar system and that it was a comet. Then, the European Southern Observatory found that the comet didn’t let a trail of dust and gas behind, so it was reclassified by the International Astronomical Union as being a rocky asteroid.
However, a study published in the journal Nature on 27 June shows that `Oumuamua is indeed a comet and not an asteroid.
Marco Micheli is a European Space Agency planetary scientist and also the lead author of the study, explaining why `Oumuamua is not an asteroid:
“The gravitational effect of the planets and the large asteroids can all be modeled very well, because we know the positions and masses of them. We took all of that into account in our analysis of the trajectory, and we noticed that an additional force was needed to explain the observations.”
That additional force can only be caused by the gases coming from a comet after its ice is heated by sunlight:
“The comet itself therefore feels a push in the opposite direction,” added Micheli.
‘Oumuamua is a Comet, Even If It Doesn’t Look “Cometary”
Micheli and his team conducted measurements to watch `Oumuamua’s path through our solar system, using the Hubble Space Telescope and the Very Large Telescope in the Atacama Desert, Chile.
Thomas Barclay is an astrophysicist at the Goddard Space Flight Center (NASA), explaining why `Oumuamua couldn’t have been an asteroid. Asteroids form in a solar system, but the icy bodies, like comets, have to form far from a sun, or else they will melt away. Most of the comets live on the edge of solar systems.
Barclay concludes that ‘Oumuamua is indeed a comet and that:
“It’s not at all that surprising that this is cometary even though it doesn’t look cometary.”
Rex Austinwas born and raised in Thunder Bay Ontario on the shores of Lake Superior. Apart from running his own podcast (Ice Fishing And Other “Cool” Things), he spends his time canoeing and backpacking in Northern Ontario.. As a journalist Rex has published stories for Global News (Thunder Bay) we well as Buzz Feed and Joystiq. As a contributor to Great Lakes Ledger, Rex most covers science and health stories. Contact Rexhere