Solar storm sparks Monday night auroras across Canada
Tuesday, September 20, 2016, 11:05 AM - A stream of solar particles sparks brilliant displays of the Northern Lights across Canada, and how to spot satellites and the International Space Station. It's the Night Sky this Week!
Monday night Northern Lights
Space weather forecasters anticipated a display of the Northern Lights to manifest across Canada, Monday night into Tuesday, due to what's known as a coronal hole high speed stream sweeping past Earth's location in space.
Based on posts to social media, the forecast did not disappoint.
G1 Geomagnetic Storm levels were reached at just before 300UTC Sept 20, or 11 p.m. EDT, on Sept 19, 2016. Credit: NOAA Space Weather
Reports of auroras were seen from many locations across the country, even as far south as Mountsberg, ON, which was below the line of expected visibility for this event.
Some of the best views came out of the Prairies, however, and much farther north, as shown below.
Where is this storm coming from, and what is a coronal hole high speed stream?
As the Sun rotates at the centre of our solar system, there's plenty of activity going on there, at and above its surface. Magnetic field lines, produced by the charged plasma gases circulating in its surface layers, loop outward and then back into the star, and can put on a spectacular display. Occasionally, though, these field lines stretch far out from the Sun and do not loop back in, resulting in what's called a "coronal hole," which allows solar particles to stream away from the Sun at high speed.
The Sun, seen at two different wavelengths of UV light, at 09:39 UTC, Monday, September 19, 2016, by NASA's Solar Dynamics Observatory. Coronal holes show up as dark patche, while magnetic field lines are shown in white. Credit: NASA
With the Sun rotating in space, these streams of particles flow outward like ribbons around a spinning skater. The large coronal hole shown above, in the bottom right quadrant of the Sun's face in each image, was pointed towards Earth at the start of the weekend, but it is tonight, when the steamer of particles finally catches up to us, that Earth will feel its effects.
Events like this pose little to no harm on us here on the surface, and while a minor geomagnetic storm can cause minor disturbances in power grids and orbiting spacecraft, they are really a great opportunity to observe one the treats afforded to us by the interaction of the Sun and Earth's magnetic field - the auroras.
Due to the predicted extent of the auroras, areas of southern Ontario - which just happen to be the heaviest light-polluted regions of the country as well - will probably miss out on the show. Otherwise, most of Canada could catch a glimpse of them. The Prairie provinces are especially good for this.
Keep a watch out, regardless of your chances, however. At times, these coronal hole high speed streams can surprise us, delivering stronger geomagnetic storms than the forecast is calling for. If the Kp index can reach up to 6 or 7 (from a G2 or G3 geomagnetic storm), all of Canada could see this one.
A few notes of caution: Light pollution will spoil any view of the Northern Lights. For people living in many parts of Canada, simply getting outside their community is enough. For anyone living in the Windsor to Quebec City corridor, though, the best option is to head north until you can see a healthy number of stars above your head.
Also, even if you are in a good position to see the aurora, it may still be quite faint, requiring a camera with long-exposure pictures to really pick out the vibrant colours. Check out the what the Tanners, from Central Alberta, have to say on the subject in one of our latest In Focus features.
Spotting satellites and the International Space Station
While gazing up at the sky, one can occasionally spot something close and bright that is not of extraterrestrial origin - a passing satellite or even the International Space Station.
Seeing these objects flying by overhead is usually just a coincidence, unless you use NASA's Spot the Station website or if you download one of the tracking apps on your phone (ISS Spotter for iPhone or ISS Detector for Android, for example). These bits of software track the orbits of these satellites and spacecraft as they circle Earth, and based on your location, they will inform of opportunities to spot them.
For example, with clear weather in the forecast for southern Manitoba for Monday night, skywatchers can catch a very bright Iridium flare, at roughly 8 p.m. Central Daylight Time.
Sept 19 PM location of the Iridium flare from the Iridium 90 satellite over southern Manitoba. The dashed line indicates that the satellite will not be visible along the path, except at the yellow dot. Credit: ISS Detector app
Starting at around 7:55 p.m., the Iridium 90 polar-orbiting communication satellite will rise above the northern horizon. However, this small satellite will be mostly invisible until roughly 42 seconds after the hour. When it reaches a point in the sky just to the south-southeast of the zenith (directly overhead), the satellite's solar panels will catch the Sun's rays and reflect them down to Earth.
No need to leave the city for this one, though. This flare is extremely bright - at a magnitude of -7.9, it will be the brightest thing in the sky at that moment - however it will last for only a second, two at the most. If you live anywhere under the large circle in the right panel of the above image, there is a chance to see it from where you are as well, but be sure to adjust for time zone and location, and be aware that it will be dimmer the farther you are away (and possibly lost in the glare of the Sun for those farther west).
Given equally clear weather on the morning of Tuesday, September 20, the Great Lakes region has the chance to watch the International Space Station flying overhead.
Sept 20 AM passage of the ISS over the Great Lakes. A solid-line path in the left panel indicates full visibility across the entire arc of its passage. Credit: ISS Detector app
Unlike the Iridium Flare, most observers will be able to see the ISS fly from one horizon to the other, as its solar panels catch and reflect the sunlight throughout nearly its entire passage across the sky.
Look for the station to rise above the northwest horizon at around 6:08 a.m. EDT, and it should track roughly directly overhead until it disappears past the eastern horizon at just before 6:15 a.m. EDT.
While this ISS flyover will not be as bright as Winnipeg's Monday night Iridium Flare (it will only be about magnitude -3.3), it will still be one of the brightest objects in the sky and clearly noticeable by its rapid passage overhead.
Checking with NASA or your phone app will afford you plenty of chances to spot these spacecraft, and they're definitely worth checking out.
Teaser image courtesy Adam Hill Studios via Twitter