Despite our increased efforts to track and devise countermeasures against near-Earth objects (NEOs), the comets and asteroids in the outer reaches of our solar system still present us with surprises. When comet P/2016 BA14 passed within 2.2 million miles of the Earth on March 22, it was predicted to have a nucleus size of around 410 feet. However, after three nights spent observing the object, NASA's Goldstone Solar System Radar in California's Mojave Desert revealed that the comet is approximately 3,000 feet wide.
The radar imagery examined by NASA revealed numerous important features of the comet's surface and could help them shed light on its origins. Although this may not give us any more comfort when it comes to planetary defense, comet research is a field that has implications for our understand of the solar system.
"The radar images show that the comet has an irregular shape: looks like a brick on one side and a pear on the other," said Shantanu Naidu, the postdoctoral NASA researcher who led the radar observations. "We can see quite a few signatures related to topographic features such as large flat regions, small concavities and ridges on the surface of the nucleus."
Although comet vapor tails appear very bright when lit by sunlight, their nuclei are actually very dark, which is one of the reasons that many uncertainties arise when measuring comet dimensions.
Using NASA's Infrared Telescope Facility (IRTF), researchers revealed that BA14 only reflects three percent of the sunlight that falls on it, a characteristic that not only makes the nucleus extremely dark, but likely caused the discrepancy in the size estimate since comet detection relies on how much light they reflect off their surface.
In addition to revealing its true size, astronomers are hoping to use the infrared spectra to uncover clues on the makeup of comets in order to better understand their evolution. In-depth studies on comets are important as they were created from the protoplanetary disk that formed around the sun prior to the formation of the Earth over four billion years ago, making them "time capsules" that could reveal the secrets of our solar system.
