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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.

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Lyrid meteor shower 2017 April 17, 2017

Posted by aquillam in Astronomy, MichiganAstro.
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The first potentially big warm weather meteor shower is coming this weekend. Predictions of the peak’s timing all place the peak during daylight in the Midwest on the 22, but this shower usually has an extended peak. In fact, you may see as many meteors on the 21 or 23.

The radiant lies in Lyra, near Hercules. It’s not really high enough to observe until 2 AM, it transits the meridian around 5:30, and it starts getting light out at about 6 AM, so the best time to observe is about 4 – 6 AM local time. Here’s a map for 5 AM with the stars of the summer triangle marked:

22Apr0500S.png

The Lyrids are an irregular shower, usually producing a mere 10 – 20 meteors per hour, but occasionally reaching rates of around 100 meteors per hour.   This year is expected to be a pretty average year, which means waiting several minutes between meteors. If you don’t have dark skies, it may mean 10 – 15 minutes between bright meteors.

 

Additional resources:

American Meteor Society guide to the Lyrids

EarthSky All you need to know: Lyrid meteors

 

Summer 2016 meteors July 26, 2016

Posted by aquillam in Astronomy, MichiganAstro.
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It’s meteor shower season, and The summer meteor showers are ramping up!

The Delta Aquariids are in progress now. Although the peak is expected to fall on July 28, this is a long, slow shower, worth watching for at least a week after the peak. Don’t expect to see a lot of meteors though. Even at its peak there are only 10 – 20 meteors per hour (or about 5 minutes between meteors.) The radiant is highest at around 3 AM this time of year, so that would be the best time to observe if it weren’t for the waning Moon in the last week of July. Going out around 1:30 – 2:30 on the 28th gives a good combination of reasonably high radiant and a low Moon.

While you’re out looking for delta Aquarius, watch for Perseids too. Luckily, Perseus isn’t far from Aquarius. Check out this story from EarthSky on how to tell them apart.

While the Perseids don’t peak until August 11 or 12, you should already be able to spot a few. The real show should be the early morning of August 12, and continue through the morning of the 13th and maybe the morning of the 14th. Some experts think this could be a spectacular year, with rates of 200 per hour at the peak (that’s about 3 meteors per minute!) Better still, a waxing moon means dark skies most of the early morning hours. The best time to view will be around 3 – 5AM, when the Moon has set, Perseus is high, and twilight hasn’t really started yet. Here is a map for 4:30 AM on August 11 with both radiants marked.

11Aug0430_SE_meteors.png

Mercury and the Moon binocular challenge June 2, 2016

Posted by aquillam in Astronomy, Urban Observing.
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Using binoculars, and a clear ENE horizon, you can spot a very old Moon and Mercury tomorrow morning. About 45 minutes to an hour before sunrise, go out and look for the bright Star Capella in the north east. Drop your view about 5° toward the horizon, and scan to the east. With a little luck, Mercury and a very old old moon will pop into view.

02June0530ENE.png