The ancient comet ‘Oumuamua (above) made waves in late 2017 as our first interstellar visitor, but of course, it wasn’t the first. It was simply the first one we ever spotted. Astronomers at Harvard University now say Earth had a much closer encounter with an alien object in 2014. That small asteroid or comet may have traveled multiple light years from another solar system to burn up over the Pacific Ocean.
Interstellar visitors like ‘Oumuamua and the unnamed meteor might be common, but we have only recently been able to detect them. ‘Oumuamua passed through our neighborhood during summer and fall 2017, but astronomers with the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS1) didn’t spot it until October 17 that year. The team confirmed it was extrasolar due to its high speed (196,000 mph) and orbital eccentricity of 1.20. We can be fairly certain at this point that ‘Oumuamua is not an alien spacecraft.
‘Oumuamua is a relatively large cigar-shaped object 1,300 feet (400 meters) in length. The newly identified meteor was just 3 feet (0.9 meters) wide when it smashed into the atmosphere on January 8, 2014. If it hadn’t burned up in our atmosphere, it would have gone unnoticed. The researchers estimate the meteorite was moving at 134,200 mph (216,000 kph) with high eccentricity. That suggests it, too, is not of this solar system.
The researchers believe the object got a gravitational boost during its long journey to our solar system, possibly from planet or star. They analyzed about 30 years of meteorite data, identifying two more events with extremely high speed. However, one of those was on an orbit that almost certainly meant it was bound to the sun. The other is questionable — it might be another interstellar visitor or it might not.
The 2014 meteor is long gone, so there’s no way to study the event. However, there may be hope to catch the next one. If there are between one and three detectable interstellar objects hitting Earth every 30 years, astronomers could plan ahead to collect more data. For example, an alert system could tell astronomers when meteors enter the atmosphere traveling at very high speeds. That would give researchers a chance to take measurements of the debris where the object breaks up, which might offer clues as to the composition of another solar system.