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    My Journey through the Astronomical Year

    Think of this as a "companion text" to this, the main web site. Not required reading, butI hope you'll find it interesting and helpful.

More September 2011 Events: Say Goodby Saturn, Good Evening Jupiter, Good Morning Mars and Hello Zodiacal Light!

Hey, it’s a great Solar System month! Say goodby Saturn, good evening Jupiter, good morning Mars and hello Zodiacal Light!

We’ll get to the details in a moment, but essentially  Saturn rides off into the sunset, Jupiter is well place in the late evening, Mars is scampering across the morning sky at full tilt, and the end of the month will mark a great time to look for the almost phantom like , but lovely and mind-blowing in its details, Zodiacal Light. (Oh – and as bonus a very, very old Moon.)

Goodby Saturn

Yes, you can get a glimpse of Saturn, especially during the first half of the month – after that you would need to use binoculars. It’s really the single most beautiful object in a small telescope, but when it’s this low inthe sky the telescopic view is ruined by looking through too much air – so just take a look and wave goodby. But don’t weep. It will be well up  in the morning sky in a few months! Meanwhile, you can find it real easy on September 1 because there’s a 4-day old moon nearby. For the next week or two, look to the west about 45 minutes after sunset.

As soon after sunset as you can pick out the Big Dipper’s handle in the northwest, follow the arc of the handle to brilliant Arcturus and then continue on down to Spica – Saturn will be just a bit north of it. Here’s a chart.

This will help you find Saturn the first couple weeks of September. Click to get a larger version. (Prepared from Starry Nights Pro screenshot.)

Good evening Jupiter!

This is not a bad trade -Jupiter for Saturn – especially for those viewing with the naked eye, or binoculars. First off, Jupiter is absolutely dazzling – brighter than any other star or planet except Venus – and, of course, the Sun. This month it is even a tad brighter than normal as we draw a bit closer to it. It’s at magnitude 2.75.

To find it, just look for a bright star rising nearly due east about three hours after sunset the first of the month – around an hour after sunset by the end of the month. (Yes, stuff generally rises 4 minutes earlier each night and that time adds up quickly.)  What’s due east? Glad you asked because this is the month to find out – just look where the Sun rises on or near  September 23, 2011. The Fall Equinox is at 5:05 am EDT on that date which means the Sun will be rising due east – a good time to make some mental notes about objects on your horizon that help you recall exactly where east is for you.

Jupiter is fun because as Galileo discovered, even the smallest telescope reveals its four brightest moons and they constantly change position from night to night. They’re even visible in binoculars, but for this you need good eyesight and you have to find a way to hold the binoculars really steady.

Good morning Mars!

Jupiter’s no speed demon. It takes it more nearly 12 years to make a circuit of the skies. But Mars is and if you watch it in the early morning hours during September you’ll see it whipping past some pretty interesting heavenly sights and near the end of the month approaching one of my favorite binocular clusters, M44 – the Beehive!.   Here’s a chart to guide your search as Mars passes from Gemini to Cancer  on it’s way to Leo.

Mars path, week-by-week in September 2011. Chart is looking east roughly two hours before sunrise. Click for larger version. Prepared from Starry Nights Pro screenshot.

A binocular view of Mars as it approaches the Beehive at the end of September, 2011. Click image for larger view. Prepared from Starry Nights Pro screenshot.

Mars is actually between Castor and Pollux in brightness – but look for it’s reddish tint and compare it with Betelgeuse for color.

Basking in the Zodiacal Light 

The last week of September 2011 will be a good time to start looking for that most elusive of Solar System sights, the Zodiacal Light. This is another morning project that fits right in with observing Mars two hours before sunrise.  You actually have a brief window when it’s visible starting about two hours before sunrise and going to about  80 minutes before sunrise. After that the twilight will drown it out.

Looking for the Zodiacal Light  is much different than looking for a bright planet. You don’t need a totally clear horizon to see the zodiacal light, or binoculars, but you do need total darkness and that means little-to-no light pollution and no  – or very little – Moon. In Septmeber 2011 the last week will be ideal. I feel I have a good shot at it from my favorite ocean-front observing point where I have a clear horizon to the east with no cities to create light domes there. Mornings in September and October –  or evenings in February and March – are the best times for folks at mid-northern latitudes to look for this.

The zodiacal light is roughly the same intensity as the Milky Way, so if you can see the Milky Way from your chosen location, then you should be able to pick up this faint glow. Like the Milky Way, it stretches over a good deal of sky. It is widest near the horizon and gets narrower as it rises towards the zenith. You want to look for this starting 120 minutes before sunrise, but I advise you also allow at least 15 minuyes to half an hour for your eyes to dark adapt. (For projects like this I frequently keep a red flashlight near my bed and use it to preserve my night vision when I get up.)  If you try to look for this later, you may confuse it with twilight. What we are seeing is sunlight reflecting off interplanetary dust particles – dust particles that orbit in the same plane as the planets – the area we call the zodiac – and thus the name for this phenomena, Zodiacal Light.

If you see it, reflect on this explanation from Wikipedia:

The material producing the zodiacal light is located in a lens-shaped volume of space centered on the Sun and extending well out beyond the orbit of Earth. This material is known as the interplanetary dust cloud. Since most of the material is located near the plane of the Solar System, the zodiacal light is seen along the ecliptic. The amount of material needed to produce the observed zodiacal light is amazingly small. If it were in the form of 1 mm particles, each with the same albedo (reflecting power) as Earth’s Moon, each particle would be 8 km from its neighbors.

For the metrically-challenged (that includes me) that means one dust particle every five miles! And that causes all that light?! Awesome!

A morning bonus!

OK, you’ve seen Mars, you’ve seen the Zodiacal Light – now make it a triple – go for the slither of a moon – the oldest piece of moon you are ever likely to see – about 28 days 8 hours –  just south of east about half an hour before sunrise on September 26. This is for mid-northern latitudes and the Eastern Seaboard – it will get older and closer to the horizon and thus more difficult to see as you move west. You’ll need binoculars and you’ll want to look half an hour before sunrise and quit looking in another 15 minutes whether you find it or not. I say that because it scares me when folks look east with binoculars too near where the Sun is about to rise. You will do serious damage to your eyes if you look at the Sun with binoculars.

So here’s what you should see.

Can you spot the Moon in this simulation. It is likely to be even harder in real life, so use binoculars, but be careful. Stop looking as sunrise approaches. (Prepared from Starry Nights Pro screen shot.)


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