A meteor shower that has never been seen before is expected to hit tonight and into the morning, and it could be spectacular.
The Camelopardalids is a one-time shooting star show.
NASA predicts it will peak from 2 a.m. to 4 a.m. ET Saturday morning, but says "outbursts" could happen any time all night.
It recommends looking near the North Star at the faint constellation Camelopardalids, or "the giraffe," located between Ursa Major (which includes the Big Dipper) and Cassiopeia.
Peter Jenniskens, a senior research scientist with the SETI Institute who first predicted the new meteor shower a couple of years ago, says meteors from this shower are expected to make a stately glide across the sky compared with those from other meteor showers.
"They will really stand out," he said.
"We expect it to be a very, very nice display," said Paul Wiegert, an associate professor with Western University's Meteor Physics Group, who thinks the Camelopardalids will be comparable with other major meteor showers such as the Perseids, an annual August spectacle that can produce up to 100 meteors per hour during its peak.
However, he acknowledges that not everyone agrees.
"There have been predictions from we won't see anything through to a meteor storm of more than 1,000 meteors per hour."
That's because the source of the Camelopardalids meteor shower is a comet called 209P/LINEAR discovered just 10 years ago that scientists don't know much about.
Meteors are small particles of dust and rock from space — usually no bigger than a pea — that hit the Earth's atmosphere and burn up as they travel through it, giving off a bright light that makes them appear as "shooting stars."
- View a star map showing the location of Camelopardalis in the northern sky relative to familiar constellations
- Meteor shower calendar
- How to photograph a meteor shower
While individual meteors can be seen on any given night, meteor showers with lots of shooting stars take place when the Earth passes through the dust and debris left behind by a comet.
'It's a great science opportunity because we can peek into the past.'—Peter Jenniskens, SETI Institute
As comets orbit the sun, they "drop these little rocks kind of like bread crumbs behind them as they travel around," Wiegert said. "Because they keep travelling in the same path over and over and over again, you eventually start to build up more and more of those little rocks."
Even rocks dropped "many laps ago" tend to keep moving along the same path as the comet. That's why annual meteor showers such as the Perseids in August are so reliable — the comet has dropped a lot of debris over the years, and the Earth passes through it every year.
However, there generally tend to be more rocks and dust closer to the comet.
Closest comet since 1983
That's why the Camelopardalids have the potential to be amazing — Comet 209P/LINEAR will be coming closer to Earth than any other comet since 1983 (when IRAS-Araki-Alcock, passed within 4.5 million kilometres of Earth), said Peter Jenniskens, a senior research scientist with the SETI Institute.
Jenniskens was one of the two scientists who first predicted the Camelopardalis meteor shower two years ago. He saw that Comet 209P/LINEAR would pass within eight million kilometres of Earth on May 29, 2014 (about 21 times the distance between the Earth and the moon). The Earth would therefore pass through the comet's dust field five days earlier.
On the other hand, since it was discovered, the comet hasn't been very "active" — it hasn't been dropping a lot of rocks or dust lately.
That means it's dim and hard to see, even with a telescope. And there may not be a lot of debris to create meteors, unless it was left behind on previous orbits a couple of centuries ago.
"What did this thing do in the 19th century? That's the big question," Jenniskens told CBC News. "If this comet was dormant, then there won't be anything. If, on the other hand, something dramatic happened in the 19th century, it could be quite a spectacular show."
In fact, astronomers are awaiting the comet's close approach with anticipation, because they want to learn about the comet's history.
"It's a great science opportunity because we can peek into the past," Jenniskens said.
It may also help answer some questions about comets that astronomers don’t know much about, such as why their activity changes over time.
Wiegert said his team will be monitoring the meteor shower with cameras that will be able to measure the exact colours of the meteors. The colours of the light produced as the comet particles burn up depend on what they're made of, so they will reveal the comet's ingredients.
Because comets are "essentially leftovers from when the planets were formed" and are thought to have brought water to Earth, information about their composition can help scientists learn more about where the Earth came from, Wiegert said.
This is a unique opportunity to study the comet, as it won't be coming back this way until June 2019, and at that time, it won't come nearly as close.
It's also probably the only chance you'll ever get to see the Camelopardalis meteor shower.
Since we don't know whether it will be a good show, Jenniskens advises you to "keep your expectations low."
"On the other hand," he said. "It's something you don't want to miss."