EDITOR’S NOTE: Ever wish for advance alert of an upcoming meteor shower/eclipse/etc. – and/or wonder “What’s that bright ‘star’ up there?” Here you go! It’s our monthly feature by West Seattle’s own Solar System Ambassador Alice Enevoldsen, famous for her solstice/equinox sunset watches among other things.
By Alice Enevoldsen
Special to West Seattle Blog
August might be your peak month for stargazing, depending on the time you have available. Whatever your reason for finding time to view the beautiful August skies, take advantage of it, and don’t miss the Perseid meteor shower next weekend. The only thing working against you is the late sunsets and early sunrises. First:
Hey! What’s That?
Venus – in the W just after sunset
Saturn – medium-low in the SW after sunset
Arcuturus – high in the W
Jupiter – low in the E before sunrise
Capella – low in the NE after midnight
Let’s talk about Aurorae (“Northern Lights”)
I’ve been tweeting very wishy-washy Aurora alerts over the last couple months. I wish I could be more specific for you, but the Aurora is one of those sky phenomena that is less predictable – just like comets.
The Aurora is so unpredictable is because it is caused by an interaction between the Earth’s magnetic field and the solar wind.
The Sun is extra-active this year because of the solar maximum that will occur this fall. When the Sun is more active, it makes the Earth’s magnetic field fluctuate more.
(“Dramatization” of the effect of the solar wind on the Earth’s magnetic field. Not to scale)
The activity in the Earth’s magnetic field is measured using the Kp number. The Kp number actually hides a fairly complicated analysis of how much the magnetic field is changing at a given time. A higher Kp number means more activity as well as activity that is farther from the poles and closer to the equator (closer to us). This implies that Aurorae are more likely, but even with very high Kp numbers the visibility of the Aurorae will vary. For Seattle we usually only have a chance at seeing Aurorae if the Kp number is 5 or above.
The Auroral oval is an image of where the Auroral activity is centered. This is simpler to understand: if there is color over Seattle then we have a chance at seeing Aurorae. If there isn’t color over Seattle we probably won’t. Still, this image is more of measure of activity in the magnetic field, and not a measure of actual Aurorae sightings.
(This is the Auroral oval from NOAA (National Oceanic and Atmospheric Administration) for August 4th at 8:30 pm our time. Red is higher activity, blue is lower activity. Please go to NOAA for the most recent oval and for detailed explanation of the graphic)
When I send out an Aurora alert to you, it is because one of my sources indicates that the Kp number is predicted to be 4 or above, because the Auroral oval is somewhat vaguely overlapping with Washington State, or because I get a Geomagnetic storm alert from Space Weather.
My sources are Soft Serve News, so by extension the University of Alaska Fairbanks’ Geophysical Institute, and Space Weather.
There’s a meteor shower coming up next weekend! You’ll want to have a clear view to the Northeast, and watch after midnight. The peak of the shower will be next Monday morning (August 12th) before 3 am. This means that you’ll go out next Sunday night (August 11th) and watch for a while.
Where should you go? Well, this time Solstice Park and Lincoln Park are not good locations because the view to the Northeast is occluded. If you’re going to stay in West Seattle, find a darker area on Alki proper (though remember that the park closes before midnight), or try Hamilton Viewpoint looking out over toward the city. West Seattle is very poorly placed for viewing the Perseids: even when you can see the Northeast, that’s where the city is. Better locations include Green Lake or driving partway across the pass to Lake Kachess.
Meteors (shooting stars) are tiny grains of sand that are burning up in our atmosphere. The biggest meteors you might see during the Perseids would probably be the size of a grapefruit, but there will be few of those.
For those of you who want more information, I’ll leave you with this: meteors are heating up due to compression heating of the atmosphere in front of them, not due to friction with the air. This is the same principle as why canned air that you might use to clean your computer gets cold as you use it.
Early Morning Sky Grouping
For those of you who rise before the Sun in the summer, and those of you who stay up until sunrise watching for the Perseids, there is a large beautiful group of bright objects in the eastern sky.
Jupiter and Mars are both in Gemini (and later Mercury if you can catch it in the glow of sunrise. Also in that area are many first magnitude stars: Rigel and Betelgeuse in Orion, Capella in Auriga, as well as Castor and Pollux in Gemini itself. Lastly, the Pleiades and Hyades star clusters are just above Orion.
We usually associate these constellations with winter, because they’re behind the Sun during the summer. As we approach winter (yes, believe it: we’re on the winter-heading side of the summer solstice), these constellations will become visible for more and more of the night.
August 12, 12 am-3 am (NIGHT of August 11, morning of August 12) – The Perseid meteor shower peak is in mid-August. You’ll see some shooting stars from Seattle, but the farther you can get from city lights, the more you’ll see. Face Northeast.
Got events to add? Please comment below.
August 20, Full Moon: The full moon rises at sunset, and sets at sunrise.
August 28, Last Quarter: The week around the last quarter moon, it is visible in the early morning sky.
August 6, September 5, New Moon: The day of the new moon you won’t see the Moon at all, but in a few days before or after you might see a tiny sliver of a crescent Moon in the mid-day sky.
August 14, First Quarter: The first-quarter moon is ideal for late afternoon and early evening observation.
Stellarium: Free planetarium software for your home computer. Bring up the sky for anywhere in the world – any time and date in history, or the future.
Clear Sky Chart: The astronomer’s forecast for the next couple days. Cloud cover, darkness, and “seeing” which is how nice it is to view the stars, all on one handy chart.
USNO: Dates and times of astronomical happenings.
Who is Alice?
Alice is many things and works and volunteers for a few different notable organizations, but the suggestions and opinions put forth in this article are her own and no one else’s. You can find more about astronomy at alicesastroinfo.com.
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