In October, 2017 astronomers at Haleakala Observatory in Hawaii discovered something strange. It was an object, moving through the solar system too fast to have been captured by the sun’s gravitational pull. It had come from interstellar space, passed the sun, and was hurtling back out into interstellar space. The scientists named it ‘Oumuamua’, a Hawaiian word for ‘scout’ or ‘messenger’.
No one has ever discovered an object from interstellar space in the solar system before. What is this thing?
At first, the researchers thought it was a comet. But comets are made out of ice and dust, and release lots of gas and dust when they approach the sun and the ices melt. Sometimes this results in a tail of gas and dust. Oumuamua didn’t do any of this, so it probably wasn’t like a typical comet. Its shape is also not like any known comet. It’s cigar-shaped, ten times as long as it is wide, and it’s spinning and tumbling in space. Its light indicates that it has a composition similar to some asteroids. Its surface is reddened by long exposure to cosmic rays in deep space.
Oumuamua has a shape unlike any natural object ever discovered in space. What if it’s not just a piece of rock? Could it be an alien spaceship?
That possibility occurred to the astronomers too, and several different teams listened to Oumuamua with powerful radio telescopes for possible signals, just in case. But, they didn’t find anything. Whatever Oumuamau was, it has now passed beyond range of our telescopes, and we may never learn anything more about it.
Reviewer: Mathew M. Knight, the University of Maryland
Read more
- Was Oumuamua a nitrogen iceberg?
- Wishing on a meteor shower's shooting stars
- Defending Earth: The impact threat
Sources
- ADS - On the rotation period and shape of the hyperbolic asteroid 1 l/'Oumuamua (2017 U1) from its lightcurve
- The Astronomic Journal - Spitzer observations of interstellar object 1 l/'Oumuamua
- NASA - NASA learns more about interstellar visitor 'Oumuamua
- EarthSky - 5 things we know, and 5 things we don't, about 'Oumuamua
- ScienceNews - Our first interstellar visitor may be a camouflaged comet
- Space.com - Interstellar object 'Oumuamua's surprise arrival still thrills scientists one year later
- NASA JPL - Our solar system's first known interstellar object gets unexpected speed boost
- The Conversation - Evidence of aliens? What to make of research and reporting on 'Oumuamua, our visitor from space
Y: In October, 2017 astronomers at Haleakala Observatory in Hawaii discovered something strange. It was an object, moving through the solar system too fast to have been captured by the sun’s gravitational pull. It had come from interstellar space, passed the sun, and was hurtling back out into interstellar space. The scientists named it ‘Oumuamua’, a Hawaiian word for ‘scout’ or ‘messenger’.
D: Yaël, no one has ever discovered an object from interstellar space in the solar system before. What is this thing?
Y: At first, the researchers thought it was a comet. But comets are made out of ice and dust, and release lots of gas and dust when they approach the sun and the ices melt. Sometimes this results in a tail of gas and dust. Oumuamua didn’t do any of this, so it probably wasn’t like a typical comet. Its shape is also not like any known comet. It’s cigar-shaped, ten times as long as it is wide, and it’s spinning and tumbling in space. Its light indicates that it has a composition similar to some asteroids. Its surface is reddened by long exposure to cosmic rays in deep space.
D: Yaël, Oumuamua has a shape unlike any natural object ever discovered in space. What if it’s not just a piece of rock? Could it be an alien spaceship?
Y: That possibility occurred to the astronomers too, and several different teams listened to Oumuamua with powerful radio telescopes for possible signals, just in case. But, they didn’t find anything. Whatever Oumuamau was, it has now passed beyond range of our telescopes, and we may never learn anything more about it.