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Venus in August 2018 August 1, 2018

Posted by aquillam in Astronomy, MichiganAstro, Urban Observing.
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Everyone else may be talking about Mars, but don’t miss your chance to check out Venus this month!


The orbits of Earth, Venus, and Mercury about the Sun, with 16º elongation and maximum eastern and western elongation shown.
The maximum elongations for Venus are shown with the dashed lines, and those for Mercury are shown with the dotted lines.

Venus orbits closer to the Sun than we do. That means from our point of view, it never gets very far from the Sun. When it is farthest in the sky from the Sun, we call it greatest elongation. On August 18, Venus will be at greatest eastern elongation, and it’ll be a little over 45º east of the Sun. That means it’ll be easy to see in the western sky for at least an hour after sunset.



Additionally, Venus will be headed for a crescent phase, which brings it closer to us, so it’ll be getting bigger and brighter. It’ll actually be at it’s brightest near the end of September.



Because of the angle of the ecliptic, it sets a lot sooner in September. Here are a couple maps showing the ecliptic from SE Michigan (or anywhere between 40 – 50º N latitude) on August 1st and 30th, both 1 hour after sunset. You can see the ecliptic moves southward, which means anything on the ecliptic will set earlier in the northern hemisphere.

W (west) is at the center bottom and NW near the bottom right corner. The ecliptic runs from the top left corner to the bottom about 1/4 of the way between W and NW.

Venus and the ecliptic on August 1st 2018, 1 hour after sunset.

W (west) is at the center bottom and NW near the bottom right corner. The ecliptic runs from the top left corner to the bottom just to the left of W.

Venus and the ecliptic on August 30th 2018, 1 hour after sunset.

So now’s the time for the easiest and latest observations of Venus, and September will be the time for the brightest and most interesting telescopic view of Venus!


Observing tips for July 4th, 2018 July 2, 2018

Posted by aquillam in Astronomy, MichiganAstro, Urban Observing.
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The forth of July brings a lot of people outside after dark. While you’re waiting for those fireworks to begin, here are a few things to look for.

I recommend taking along a pair of binoculars.


Venus and Mercury in the West July 3, 2018, 9:30 PM.

Start about half an hour after sunset (or about 9:30 in SE Michigan) and look west. About 20º ( 2 sideways fists) above due west is Venus. As the skies darken, it stands out like a beacon! look 16º (index finger to pinky) down and to the right for Mercury. Mercury can be a tough object to spot because it’s never far from the Sun, so it’s never visible in really dark skies. The first map is for July 3, 9:30 PM in Ann Arbor, but should be good for the 4th as well.


Jupiter and Saturn in the south at 10 PM July 4

Fireworks usually begin around 10 PM (especially if you’re farther north.) Get a seat facing south for some of the summer’s best celestial show. Jupiter is about 30º above the southern horizon, and Saturn about 10º up in the SE. While you’re looking that way, be sure to check out Scorpio and Sagittarius too. Bright Antares, the heart of the scorpion, falls between Jupiter and Saturn right now.

With binoculars or a small telescope, you can pull in the 4 brightest moons of Jupiter. They’ll be lined up in a tight row on the 4th, which helps make it easier to pick them out at low magnification.

From left to right, Io, Europa, Jupiter, Ganymede, and Callisto

The Galilean Moons of Jupiter at 10 PM July 4, 2018.

If you actually have a small telescope and can pull your eye away from Jupiter, check out nearby Zubenelgenubi, a nice double star whose name means “southern claw” because it was once considered part of Scorpius.

Saturn is sitting on the top of the teapot. If your skies are dark enough later in the evening, you’ll be able to see the Milky Way trailing up the sky next to it. With binoculars or a small scope, the rings should be visible, if only as a strangely oblong shape. Some of the brighter moons may also be visible, though they aren’t nearly as easy as Jupiter’s moons.

From left to right, Iapetus, Rhea, Saturn, Tethys, and Titan, which is actually much lower that the other moons.

Saturn and its moons, July 4, 2018 at 10 pm

It’s early days yet for Mars, but if you’re out past midnight, look back to the same are Saturn was at 10 PM. Mars rises ESE around 11 PM, so it’s up nearly 10º in the SE at midnight. It’s the brightest thing in that area right now, and only getting brighter, so if your skies are clear, it’ll be hard to miss. Keep an eye on it the rest of the month as it moves toward closest approach on July 31!

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.


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.


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


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.