Put on your nice clothes, comb your hair and spend more than two bucks on some wine … we have visitors from another solar system! Astronomers have spotted a previously unknown comet passing through the solar system and it doesn’t seem to belong to our Sun. If that’s true, this is the first known observation of an interstellar comet from another solar system.
The International Astronomical Union Minor Planet Center announced that astronomers using the PanSTARRS 1 telescope in Maui (nice work if you can get it) discovered C/2017 U1 on October 18th. Further investigation showed that this tiny (diameter of 160 meters or 525 feet) dim comet had already made its closest approach to the Sun on September 9th when it was 37,600,000 km (23,400,000 miles) away from it … close enough to no longer exist. And yet … there it was pulling away at an unusually high speed (16 miles /26 km per second, or 57,600 mph) peed for a comet. Dynamicist Bill Gray from the observatory observed:
"It went past the Sun really fast and may not have had time to heat up enough to break apart."
Dynamicist? According to Collin’s English Dictionary, that’s “a person who investigates and researches dynamics. a new kind of scientist: not primarily an astronomer, not a fluid dynamicist, not an applied mathematician, but a specialist in chaos.” “A specialist in chaos” sounds more like a staff job in Washington but Gray is using his talent for a good purpose in a great location. The “chaos” he saw was a comet passing through the solar system at a very high inclination (122°) with respect to Earth's orbit with an extreme (very narrow and tight) hyperbolic eccentricity (1.1815 ).
Put C/2017 U1’s speed, high inclination and eccentricity together and you have the description of excellent rock drummer … and an interstellar comet. (Throw in ‘specialist in chaos’ and you have a great rock guitarist. ) The only other comet ever observed with these characteristics was C/1980 E1, discovered by Edward L. G. Bowell in 1980. While it was later shown to be a regular comet, C/1980 E1 is now believed to be interstellar, having been kicked out of our solar system by Jupiter’s gravity.
Where did C/2017 U1 come from? While all other comets originate in the Kuiper Belt beyond Neptune or the Oort Cloud on the far edge of the solar system, this one appeared to be coming from the constellation Lyra, which means it could be orbiting Vega, the star of Carl Sagan’s novel and the movie Contact.
Unfortunately, Bill Gray kills his chances to be a character in the sequel.
"Once one of these objects gets kicked loose, it'll roam the Milky Way for billions of years. Massive amounts of material were ejected from the solar system when it was formed; much of it is probably still wandering around, having gone around the galaxy over a hundred times. Other stars, we may assume, have similarly scattered bits all over the place."
In other words, it could have come from any star in any galaxy. Astronomers believe this is the only interstellar comet they’ll see in their lifetimes so they’re analyzing the heck out of it before it’s gone. The rest of us can see what it looked like using the JPL Small-Body Database Browser (requires Java).
If there’s one interstellar comet, there’s more. Will this finally legitimize the theory of panspermia? Will it convince more kids to become dynamicists?