This week marks one year since astronomers happened upon an unusual object moving through space not too far from the Earth’s orbit. After a few days, they realized it could not be an ordinary asteroid or comet because its path demonstrated that it was not gravitationally bound to the solar system. Thus, it became the first interstellar body ever found in our solar system that came from outside it. It was given the Hawaiian name ‘Oumuamua, meaning “scout.”
As Asgardia works toward building a demilitarized and free scientific base of knowledge in space these types of discoveries could prove useful.
For a long time, Astronomers believe that comets and asteroids exist in other planetary systems and it’s possible that ‘Oumuamua came from one of them. Most present models of our solar system propose that such small bodies are leftovers from the era of planet formation, and other planetary systems should also have generated comets and asteroids. Examining them would provide robust insights into the similarities and differences in planetary system formation. However, to date, it has been impossible: the presumed large populations of comets and asteroids discovered in exoplanetary circumstellar disks are far away, and their individual members are faint and spatially unresolved.
Thus, Oumuamua might be a rare scientific resource, and so it became the subject of an intense, albeit brief, observing campaign—short because it was so fast-moving that it quickly became too distant and faint to see. Regardless, the observations that were done found that it was reddish in colour, with no apparent spectral features and no signs of gas or dust. All these suggest it might be something like a primitive (“D-type”) asteroid, but truthfully there is no good analog known in our solar system. Most notable of all, as it rotated its variable light curve showed that it has a very elongated shape: six times longer than it is wide.
The IRAC camera that lies on the Spitzer Space Telescope is presently around 155 million miles from our planet and had a very different viewing angle toward ‘Oumuamua than the Earth-bound telescopes did. CfA astronomers Joe Hora, Howard Smith and Giovanni Fazio, in conjunction with their long-standing team of Near Earth Object scientists and other colleagues, pointed IRAC at the spot in the sky where predictions placed ‘Oumuamua (since it is not bound to the solar system and moves so fast ‘Oumuamua’s path in the sky was comparatively hard to calculate).
After a long period of 30 hours of staring, the object was not detected. However subsequent orbital analyses confirmed that the camera was pointed in the right position toward it. The limit to its emission, however, was so low that it allowed the team to constrain some of its physical properties. For instance, the lack of an infrared signal suggests it has no gas or dust, species that would be expected if it were a cometary-like body. The scientists also calculate that, based on its exact composition and reflectivity, Oumuamua is at least 240 meters (and maybe as much as one kilometre) in its longest dimension (for those who love Star Trek, some fans estimate the length of the Enterprise to be 725 meters). The object has now moved too far for any of our telescopes to see it and will remain an interstellar mystery. But it reminds us that our cosmic neighbourhood is full of surprises.
If you’re intrigued by all the surprises, the universe has to offer then join Asgardia today and network with forward-looking people.