What's Up In Space?: Aurora watch and meteor showers
Tuesday, April 21, 2015, 8:38 AM - It's pretty active in Earth-space this week, as a bus-sized asteroid is set to whiz by, and an eruption from the Sun is set to spark auroras overnight into Earth Day. It's an early edition of What's Up In Space!
Newly-found asteroid to zip past Earth
If you weren't aware, there are a LOT of asteroids flying around in space - even in the relatively 'clear' space around Earth - and more being discovered all the time.
One of the latest finds, which made a close-pass by Earth early Tuesday morning, is a roughly 15-metre wide asteroid that now goes by the name 2015 HD1.
The approximate path of 2015 HD1 through the Earth-Moon system. Dark blue path is below the ecliptic; light blue is above. Reference: NASA JPL/Caltech. Credit: Scott Sutherland.
Spotted over the weekend at a distance of over 4 million kilometres away, 2015 HD1 passed inside the orbit of the Moon to within around 59,000 kilometres of Earth - less than one-sixth the distance to the Moon!
Although astronomically-speaking that is a very close flyby, just outside the ring of geosynchronous weather and telecommunications satellites that orbit our planet, 2015 HD1 is not considered to be a threat. A 15-m asteroid entering our atmosphere is certainly nothing to discount, of course. However, the orbit of this particular asteroid - taking 3.29 years to go around the Sun - is just too far out-of-sync with Earth's orbit to be a potential threat. This is apparently the first time we've seen this rock since August of 1923, and we won't likely see it again until sometime after the year 2200.
Watch Out for Earth Day Auroras
Looking for a fairly unique way to celebrate Earth Day? How about watching displays of the Aurora Borealis?
Thanks to an Earth-directed coronal mass ejection (CME) that erupted from the surface of the Sun on Saturday evening, Earth will very likely be experiencing a weak geomagnetic storm from Tuesday night into Wednesday morning.
The above video shows a NOAA Space Weather Prediction Center plot of the CME as it speeds through space towards Earth. Due to the shape of the CME and its interaction with the solar wind, the densest parts of the plasma cloud will pass to either side of Earth. This will result in a glancing blow on the planet's magnetic field sometime in the afternoon, Eastern Time, on Tuesday, April 21 (the video uses Universal Coordinated Time, or UTC).
As we've already seen recently, such as the St. Patrick's Day geomagnetic storm, even a glancing blow by one of these CMEs is capable of sparking some particularly intense and beautiful displays of the Northern Lights. Auroras may even stretch reach far enough to the south that they could be visible to the majority of Canada.
Local sky conditions on Tuesday night and Wednesday morning will have the biggest impact on the visibility of this event. Just by the timing of the geomagnetic storm forecast, though, the best viewing should be from Atlantic Canada after sunset through to the Prairies closer to midnight. After that, the geomagnetic storm is expected to die down, but the auroras could still be active for the rest of the night.
Check back (or follow @ScottWx_TWN on Twitter) for more updates.
Bonus: Lyrid Meteor Shower Peaks This Week
More on this closer to the actual night in question, but the Lyrid meteor shower reaches its annual peak later this week.
If the skies are clear in your area, this should be an especially good year to watch this meteor shower, since the waxing crescent Moon will only be shedding a small amount of light on Wednesday and Thursday mornings (the best time to check it out).
Under prime viewing conditions, such as from a dark sky preserve, one can expect to see between 10-20 meteors flash across the sky every hour. This shower is known for producing the occasional fireball meteor as well.