Canadian Radar Detects gamma Lyrid Shower for Second Time Ever
You may be familiar with some of the well-known meteor showers like the Perseids or Leonids, but have you heard of the gamma Lyrids? If not, you’re not alone — this shower is new to NASA as well.
The gamma Lyrid shower was first discovered using the Canadian Meteor Orbit Radar (CMOR) in 2015 and was not seen again until Feb. 5, 2018, when it didn’t just appear, but showed a significantly stronger outburst than three years ago.
“This shower was surprisingly strong in terms of flux,” said Althea Moorhead, aerospace technologist for planetary studies.
The level of activity was especially unusual, she explained, for an obscure shower that’s only been seen twice. The flux, which produced an increase of 4 percent in total meteor activity, is why she feels it’s worth the effort of exploring more in depth and modeling down the road.
Although the gamma Lyrids appear to be a relatively new shower, it is possible they appeared prior to 2015 but weren’t noticed. Newer algorithms that allow monitoring in near-real time make it much less likely than before that outbursts will be missed.
“This shower, for some reason, seems to be only detected by radar,” said Moorhead.
According to Moorhead, the gamma Lyrids occur right before dawn, making it difficult to see them against the twilight sky with either cameras or the naked eye. In addition, in both 2015 and 2017 they occurred while the moon was very high and full, making them even more difficult to spot with cameras.
Unlike traditional cameras, CMOR is a meteor radar that transmits a broad radar beam and detects the radiation that reflects off meteors as they pass through the atmosphere. It is capable of “seeing” in a wide range of directions within the northern hemisphere and can detect meteors day and night. In fact, according to Moorhead’s estimates, CMOR can see approximately 80 percent of the sky over the course of the day with regards to meteor directionality.
Since CMOR has been in multi-station operation for a little more than 15 years and there’s flux data going back to 2007, what Moorhead and NASA’s Meteoroid Environment Office (MEO) can say with confidence is that the gamma Lyrids have not been present within CMOR observations between 2007 and 2015.
Identifying the Outburst
CMOR is operated by the University of Western Ontario, and NASA has an agreement with the university to use that data to help meet the agency’s monitoring needs. The university has a number of tools that automatically analyze the data it captures and send it to NASA on a daily basis.
When NASA received the data for Feb. 5, it showed a concentration of meteors that didn’t match the agency’s traditional models for that time of year. According to Moorhead, MEO didn’t initially remember the shower from 2015, as it was rather obscure.
“The outburst kind of took us by surprise…again,” said Moorhead.
Although it’s not uncommon for there to be unexpected small showers, the strength of this outburst was unusual.
But what makes a shower and its outbursts so variable? While not much is known about the gamma Lyrids, including its parent body, in general, showers can be variable because they are young or perturbed by the gravitational pull of other planets, but to know why with any degree of certainty, the shower needs to be modeled.
“Unfortunately without knowing more about how the stream formed and how it evolved over time, it would just be wild guesses,” said Moorhead.
MEO is interested in modeling the shower in the future to learn more about the gamma Lyrids themselves, but also to improve its forecasts, which inform programs and projects about the type of environment their spacecraft may encounter during missions.
Although it’s not possible to predict, yet, exactly when the gamma Lyrids will reappear, Moorhead said it will be interesting to see if they happen again in 2021, repeating the three-year gap between the first two showers.