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Eclipse glasses are not the only safe way to view an eclipse August 18, 2017

Posted by aquillam in Astronomy, MichiganAstro.
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So here it is, a couple days before the eclipse, and there are no eclipse glasses to be found anywhere. You tried calling the nearest observatory, but there’s no one there because they’ve all gone to the Path of Totality! What will you do?? How will you watch this once-in-a-lifetime event??
Calm down. It’s ok. Just go to your kitchen and grab a paper plate and a pen or pencil. No paper plates? That’s ok, any heavy paper will do. An index card, card stock (like that birthday card you haven’t recycled yet), the subscription cards that fall out of magazines, or anything that you can hold horizontally and it doesn’t droop too much. If you have an empty but unflattened box, that’s even better, but skip down a couple steps.
Once you have your piece of heavy paper and a pen or pencil, you’re ready to make a simple projector. Take the pen or pencil and poke it through the paper.
To use it, go outside, hold the paper horizontally and look at its shadow on the ground. In the middle of the shadow will be an image of the Sun! It’s a bit better if the ground is smooth, but during the eclipse it won’t really matter.
The cleaner and rounder the holes are, the better. If you have a little more time, you can make a big hole and tape a piece of foil over it, then poke holes in the foil. This makes it easy to try patterns, like these NASA folks
If you have an unflattened box and some time, grab that foil and make a cereal box viewer.
While you’re at it, try some experiments: (here’s the part that totally blew my mind back when I was an undergrad) the shape of the hole doesn’t matter that much. Make square, rectangular, triangular holes. Pull out those fancy scrapbooking paper punches. The image of a light source will always be the shape of the light source as long as the hole isn’t too big!
And that brings us back to the kitchen, because colanders are a whole lot of fun at eclipses!
With all of these “pinhole projectors” remember, they’re projectors: look at the image on the screen (or ground)!
Finally, keep some perspective. It’s not really a once-in-a-lifetime event, unless for some reason you are completely unable to travel. There are, on average, 2 solar eclipses per year, though only about half of them are total. Also, they have an annoying tendency to be visible only in really inconvenient places, like the middle of the ocean, or above  the arctic circle. It might not be easy, but it IS possible.

Tips for teaching intro astronomy July 12, 2017

Posted by aquillam in Science, teaching.
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First and foremost: this may be the only science class some of these people ever take, so think carefully about what you want them to get out of the class.

  • How do you want to change them? What do you want them to remember 20 years from now, even if they don’t specifically remember that they learned it in this (or any other) class. Always keep this in mind when making lesson plans.

Make lesson plans

  • A complete, formal lesson plan includes goals for the unit (usualy a chapter from the text), the most important ideas, a brief outline of the lecture material, notes on potential problems, topics covered in lab/discussion and homework, and what details will come from the book only.
  • If you don’t do a formal, complete lesson plan, at least write down the items from the unit you want to change them, the items they need to understand future units, and the items you want them to know for the exam. If the only thing you have is items you want them to know for the exam, consider dropping the unit.

Be aware of student expectations

  • Many students take astronomy thinking they will learn things like the names of constellations, mythologies, or how to read a sundial.
  • Many students take astronomy because they are afraid of taking a “hard science” class like physics or chemistry, or they think astronomy will have less math.
  • Be up front with them about the topics covered and the necessity of using math as well as fundamental physics, chemistry, and possibly geology and biology.

Don’t repeat the book

  • The book is expensive. If you’re just going to repeat it, don’t make them buy it. Instead, cover the material from a different angle, point out connections students are likely to miss in the reading, address common misconceptions, and use active learning techniques to engage the students and increase their level of understanding (in other words, make reading the book homework, and use class time for homework-like activities.) Let the book fill in details like numbers or specific features. Don’t add extra details unless it’s to tie things together or involves a discovery too interesting to skip or too recent for the book.

Be aware of deadlines

  • Know when the last day of drop-add is and be prepared for students who add the class on that day.
  • Make sure there is enough evaluated work or sample of the exam so students can assess whether or not they should drop before that day.

 

Summer solstice 2017 June 19, 2017

Posted by aquillam in Astronomy, MichiganAstro.
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The June Solstice occurs at 04:24 UT on June 21, 2017. That’s just after midnight EDT, so for most of the US the solstice falls on the 20th!

Here in Ann Arbor, the longest day of the year will actually be the 20th, despite the solstice falling on the 21st. That’s because we’re far west in the time zone, our clocks are ahead of the Sun. A bit farther east, say in New York, the 20th and 21st are basically equal in length. That’s more what you’d expect for a solstice close to midnight.

So enjoy the half second or so of extra darkness on the solstice.

Saturn Opposition 2017 June 16, 2017

Posted by aquillam in Astronomy, MichiganAstro, Urban Observing.
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It’s summertime, and that means Saturn-time!

But why is that?

A year on Saturn is a bit more than 29 years on Earth, which means Saturn moves about 12º along the ecliptic each year. For comparison, the Moon moves about 15º per day, so in a whole year, Saturn’s position will change less than the the Moon changes in a single day! It fact it’s so little that it take Saturn an average of two years to move through each zodiac constellation. Last year Saturn crossed the boundary into Ophiuchus (between Scorpio and Sagittarius), and it won’t leave until December. That means Saturn will be visible in the evening at about the same time this year as it was last year.

Ophiuchus is often called the 13th zodiac because itt sits between Scorpio and Sagittarius

Saturn takes 29 years to make a complete circuit of the ecliptic

Of course 12º isn’t nothing. Each year opposition drifts just a little farther east along the ecliptic, so the date changes. And since there are 360º in a circle and 365 days in a year, the date corresponds to roughly a degree per day! This year, opposition was June 15th. In 2016, it was June 3, and in 2015, May 23. Next year, opposition will be June 27.

By the way, opposition is when something (like Saturn) is opposite something else (like the Sun) in the sky. So when Saturn is at opposition, it rises at sunset, then sets at sunrise. Each night it rises a little earlier, so the weeks following opposition are the best time for evening observers to get a look. Closest approach is always close to opposition too, so the planet will be bigger and brighter than usual.

elpOrbitsOpp

At opposition, the Sun, Earth, and outer planet are on a line with the Earth in between.

elpOrbitsClose

Because the orbits aren’t circles, the Earth may get closer to the outer planet a few days before or after opposition.

 

So enjoy summertime Saturn while you can. In about 4 more years, it’ll be fall when Saturn’s out.