Observatory night cancelled

Unfortunately, the weather looks pretty bad for tonight, so we won't be going to the observatory. I'll reschedule for some time later this week or next. Stay tuned!

Meanwhile, here's a stunning time-lapse video of the night sky taken from La Palma in the Canary Islands (click photo for YouTube link). WOW.

Aurora watch

Animated GIF of the two recent
solar flares, from spaceweather.com

The Sun emitted two large solar flares on Friday and Saturday, so there's a good chance we might see some aurorae (northern lights) over the next few days. That happens when the high-energy particles spewed out by the Sun hit Earth's magnetic field, get funneled down toward the north and south (magnetic) poles, and then enter the atmosphere and ionize the atoms they come into contact with. When those ions recombine, they emit light of many colors: usually green, but sometimes also red, pink, or blue. We can see these at night as sheets or curtains of eerie, flickering light.


It's easiest to see aurorae from more northern latitudes, but when there's a solar flare, the light display can sometimes be seen further south than usual. The website spaceweather.com keeps a real-time log of where the aurorae can currently be seen, and also posts viewers' pictures. It's worth keeping an eye on this site over the weekend. If it looks like we'll be able to see aurorae from Denver, you'll want to find a spot with a nice dark northern horizon. Let your eyes adjust to the dark and look for greenish light that looks sort of like thin clouds, except you can see stars through it and it shifts around faster than a cloud does. That'd make a great observing log entry! Have you ever seen the aurorae before?

A beautiful aurora shot from Norway by Andy Keen, www.aurorahunters.org
(posted on spaceweather.com)

 

They blinded me with science!

Post your scientific article from the TP 3 assignment here. Include your name, your topic, and the title of the article. Then provide a link to the full article.

To make a clickable link, use the following format (just type it right into your comment window):

<a href="http://link-address-here.com">Clickable text here</a>

IMPORTANT NOTE: Please check to make sure your comment appears after you post it! (That is, reload the page and see if you can see it.) If it doesn't, or if you have technical difficulties while posting, please email me your link as a backup. I have to count this part late if I don't see your comment here or get email from you by 4 PM on Friday.

Here's a paper I found recently about observations of a nearby, fairly young star that is surrounded by dust and might be forming planets: Toward Understanding the Environment of R Monocerotis.

Projections

Remember how the seasons simulator shows a little Sun circle projected onto the Earth? I never thought much about it, but it turns out that circle is greatly exaggerated in size. Web comic author and über-geek Randall Munroe calculated exactly how big it is, and did the same for a bunch of other astronomical objects. Check out the full comic here (and make sure to read the hidden hover text)!

Fun fact: Munroe has an asteroid named after him (it's in the comic too)! What would you name an asteroid if you had the chance?

Midterm prep

Here are the answers to the midterm review questions I handed out in class. On Tuesday 10/8, we will review topics for the exam. What you would like me to talk about specifically? Let me know in the comments.

1.  b
2.  Prometheus, Mimas, Tethys, Titan, Phoebe
3.  4 times farther
4.  c
5.  increase
6.  d
7.  b
8.  e
9.  about 2000; 23 times bigger
10.  91 days
11.  a
12.  4 times farther
13.  I got about 1000 square miles, but answers will vary. Note that Los Angeles is about 500 square miles in area.

Good luck with your studying!