jump to navigation

Elusive Mercury in the Evening December 1, 2017

Posted by aquillam in Astronomy, MichiganAstro, Urban Observing.
Tags: , , , ,
add a comment

This weekend promises amazing weather for December in SE Michigan. Take advantage of it by looking for the elusive planet Mercury!

Sunset on December 1 in A2 is at about 5:03 PM, and Mercury sets at about 6, so grab a pair of binoculars and go out between roughly 5:15 – 5:45 and look low in the SW. Be sure to check out Saturn too: it’ll disappear behind the Sun soon! The image below is for 5:30 on Friday December 1, 2017

As the days progress, Mercury gets closer to the Sun in the sky (yes, it’s in retrograde), so by the 5th or 6th it’ll be all but impossible to catch! Conjunction is on the 12th. Saturn conjunction is December 21. 01Dec1730SW_Mercury.png

Advertisements

Venus and the Beehive August 30, 2017

Posted by aquillam in Astronomy, MichiganAstro, Urban Observing.
Tags: , , ,
add a comment

If you happen to be up around 6 AM local time the next few mornings (August 31 – September 2, 2017) grab a pair of binoculars. Venus skims past one of my favorite open clusters in the pre-dawn hours.

Look east, between the Big Dipper and Orion, just below Gemini. You won’t be able to miss Venus. It’ll even shine through light cloud cover! If it’s clear, point your binoculars that way and you’ll see the Beehive cluster, so called because it sort of looks like a bee skep tipped on its side with the bees buzzing around it (a skep is the round, woven grass type of beehive.) It’s a fairly bright cluster, so even a small pair of binoculars will do. You probably won’t want to haul out the telescope for this because you need a 2º field of view, which most telescopes won’t do.

If you live in really dark skies, plop a camera down on a tripod and try taking a 1 – 2 second exposure. Longer will capture more stars, but overexpose Venus.

Here’s a chart looking east at 6 AM on August 31 from Ann Arbor:

31Aug0600E

Saturn Opposition 2017 June 16, 2017

Posted by aquillam in Astronomy, MichiganAstro, Urban Observing.
Tags: , , ,
add a comment

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.

Venus brightest around February 16 | EarthSky.org February 16, 2017

Posted by aquillam in Astronomy, MichiganAstro, Urban Observing.
Tags: , , ,
add a comment

If it’s clear where you are this evening (or the next several evenings really), look high in the west about half an hour after sunset. That incredibly bright point of light you see is not a star, it’s Venus! If you happen to have a small telescope or good pair of binoculars, take a look at it. You’ll see it’s actually a crescent!

As long as you’ve got your telescope/binoculars out, be sure to check out the little red point nearby. That’s Mars. In fact, it’s pretty much a full Mars. How can two planets be so close in the sky and so different in appearance? Because one of them is nearby, almost between us and the Sun, while the other is far away, with the Sun in between.

For more on Venus, check out this story from Earth-Sky:

 

Venus is brighter around February 16-17, 2017 than at any other time during its ongoing, approximate, 9.6-month reign in the evening sky.

Source: Venus brightest around February 16 | EarthSky.org