Fireball over southern Ontario may be debris from famed Halley's Comet
Monday, May 5, 2014, 1:18 PM - The bright fireball spotted in southern Ontario on the afternoon of Sunday, May 4, 2014, may have been a piece of debris left behind by Halley's Comet.
At roughly 4:17 p.m. ET on May 4, a meteoroid entered Earth's atmosphere east of the Greater Toronto Area (GTA), producing a bright meteor trail that was visible, even in full daylight, for hundreds of kilometers around the area. Witnesses took to social media to report hearing sonic booms and seeing the meteor, and even better, some managed to capture the event on car dashboard cameras and even take pictures of the trail of smoke it left behind. This particular video was captured on a dashcam by David Narciso, a resident of Toronto, who then zoomed in on the action and slowed the video down so that we could see as much detail as possible:
Professor Peter Brown, who heads up the Meteor Physics group at the University of Western Ontario, told The Canadian Press that from all the reports and the shockwave picked up by the group's infrasound detectors, the energy released by this fireball was equal to a few tons of dynamite. Knowing this gave enough information to estimate the size and mass of the object, which Brown said was somewhere between 50-100 centimeters wide.
Are we seeing a pattern here?
On February 15, 2014, a 20-ton asteroid entered the atmosphere and exploded over Chelyabinsk, Russia. As this asteroid had never been spotted before this encounter, there was absolutely no warning of it beforehand. On the same day, roughly 16 hours later, 30-kiloton asteroid 2012 DA14 (now known as 367943 Duende) - which astronomers had been tracking for some time - passed so close by the Earth that it flew inside the ring of geostationary satellites we have in orbit. Less than two months ago, a bright fireball lit up the night sky near Yellowknife, and then a little less than a month ago, a similar fireball burned up over Murmansk, Russia. Then, just two weeks ago, representatives of the B612 Foundation released a video that used data collected and processed by Brown, which showed that three have been 26 major impacts - ones that impacted or exploded with the energy equivalent of at least a one kiloton nuclear bomb - since just the year 2001!
Meanwhile, reports of fireballs have been increasing over the past few years. In 2009, the American Meteor Society (AMS) logged nearly 700 events, in 2010 they racked up almost 950, and this increased to over 1,600 in 2011, over 2,300 in 2012, and over 3,500 in 2013. This event over Central Ontario was the 1,062nd event recorded so far this year, and there have been another seven reported since then.
So, are we seeing more of these fireballs and asteroids, and does this signify something ominous on the horizon?
It may be that we actually are seeing more of these events, but that doesn't mean that more of these events are necessarily happening. The AMS estimates that several thousand fireballs burn through Earth's atmosphere every day. The only reason we don't see more of them is that, at any particular moment, roughly half the planet is exposed to the full brightness from the Sun, which tends to 'drown-out' the light from most fireballs. Also, another significant percentage of the Earth (on day and night sides of the planet) has overcast skies, so clouds are blocking the view. This is what happened west of Montreal last November 30th. Add to that our tendency to cluster in urban areas with a lot of light pollution, not to mention being indoors and asleep during the peak times to see these events, and the fact that we don't tend to walk or drive around with our eyes locked on the skies (since that leads to accidents), and it's easy to see how we miss the majority of them.
So, what's behind the up-tick in reports over the past several years? It most likely comes down to awareness. As more people have begun carrying smartphones and being active on social media, these events have definitely received more attention, and we're looking up more often (when it's safe to do so). Also, more people becoming aware of the efforts by the AMS and the Royal Astronomical Society of Canada (RASC) to record these events likely has more of us logging on to report what we've seen (especially since Chelyabinsk).
What about this event?
Although it's possible that this fireball was completely unrelated to any other event (what scientists call a 'sporadic'), there's a chance that this one was part of a regular meteor shower that's going on right now.
At this moment, the Earth is making its first pass of the year through the trail of debris left behind by Halley's Comet, which is producing the Eta Aquariid meteor shower in our nightly skies, and this shower is reaching its peak over the next few days. The 'radiant' of this meteor shower (the point in the sky where the meteors seem to originate from) is in the constellation Aquarius, and this point is 'leading' the Sun as it tracks across the sky. This means that the best time to see the shower is in the hours just before dawn, when the meteors will flash from east to west, but at 4:17 in the afternoon (when this fireball was witnessed) the radiant is approaching the western horizon. Since the fireball flashed from west to east, it's possible it was from the same debris trail as the meteor shower.
Is there a danger from these meteoroids and asteroids?
Most certainly there is. The majority of the objects that enter our atmosphere are small and pose no threat, but there are many out there in space that are larger. Astronomers discover and track these objects on a regular basis, and there are warning systems in place if we think that one is going to stray too close to us. However, being able to detect these depends on their size and how close we are to them, and even where they are as they approach. The Chelyabinsk asteroid came at us from the direction of the Sun, where we couldn't see it until it was already blasting through the upper atmosphere.
There are telescopes on the ground and satellites in space that watch for asteroids, but the direction of the Sun remains a big blind-spot for us. The B612 Foundation is attempting to put a crowd-sourced asteroid-detection satellite into an orbit roughly the same as Venus', to watch for any of these rocks that might fly past it headed for Earth, but they need more help before they'll get the mission off the ground.
Watching the Eta Aquariids
While seeing these fireballs are a spectacular and sometimes rare event for anyone who witnessed it, the peak of the Eta Aquariid meteor shower over the next few nights will give a great opportunity to see lots of smaller meteors streaking through the sky. The best time to view the event is an hour or two before sunrise, which is when the radiant rises over the eastern horizon. Pick a spot away from light pollution if you can, and the best direction to look is just straight up. Check your local forecast for sky conditions, or the Clear Sky chart for your area to see if you'll have good viewing conditions.