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  • Rapt in Awe

    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.

Events December 2011 – Eclipse, Planets galore, and a very starry Christmas!

Let’s start with that very starry Christmas – I’ll be brief. If you like Christmas lore, the sky certainly cooperates this Christmas with brilliant Venus playing the role of the Christmas Star low in the southwest shortly after sunset. The sky at that time should look about like this:

Click image for larger version - Stellarium screen shot.

Click image for larger view.

And to identify what you’re seeing in the image above, click this thumbnail of the same scene.

Now – without going into great detail, suffice it to say that the Christmas Star lives in the hearts of believers,  as well as those for whom a bright star simply is a charming symbol of the season, as is a decorated tree or wreath. However, theologians and astronomers have put forth various theories over the years about what star, or comet, or combination of planets might be the “star” referenced in the Bible, and I’ve yet to encounter a single, credible explanation that makes me say – ah, that’s what it was!

But what we do have in the Christmas sky every year at this time is an asterism called the “Northern Cross.”  This is our old friend, Cygnus the Swan, who when rising in early summer appears to be flying south. Now he’s diving into the ground in the northwest and his main stars are much easier to make sense of as an upright cross asterism. The other identified stars on the chart  – Vega, Altair, and Deneb – mark the familiar “Summer Triangle,” which gets in one last shot before the wintry blasts descend on us.

And the Star of Bethlehem? Well, this year you might want to choose Venus to represent it as it begins a winter-long – and  brilliant – stand as our “evening star,” warming up the winter western sky with its shadow-casting radiance.

Great lunar eclipse as long as you don’t live where I do ;-(

My friends in Australia will have a great seat for this show on December 10-11. I won’t. Although the farther west you go in the US, the more interesting it gets, especially for early birds.

Essentially, a lunar eclipse starts with a “penumbral” eclipse, and this may give casual readers of various eclipse sites the idea that we in the east will see more than we actually will. Even on the East Coast of the US the penumbral stage of the eclipse will be underway just before the Moon sets – and that’s just half an hour before dawn.  But even under the best of conditions I find  the penumbral eclipse less than exciting – heck, I find it barely detectable. What it means is the Moon is entering the outer – dimmer – part of the Earth’s shadow. This will barely dim its light. And for us on the East Coast this will be especially difficult to notice with the Moon low in the west and us well into twilight.  So I’ve resigned myself to waiting until the next total lunar eclipse  April 14,15 of 2014 – which will be seen here.

But – elsewhere this eclipse  gets a lot more interesting. Here’s how NASA sums it up with a graphic on their eclipse web site – OK, you may need a little rocket science training to read this, but not much – be patient 😉

NASA eclipse details - see below for explanation. (You can click on this for a larger version.)

The important numbers here are in Universal Time.  To translate to your local time  go here.

The Moon enters the penumbral shadow at 11:33 Universal Time – that’s “P1” in the above graphic. For me in Massachusetts, that is 6:33 am on December 10.  For my friend John, in Oregon, that’s 3:33 am on December 10. And for my observing friends in Sydney, Australia, that’s  21:33 – 10:33 pm on December 10. See how things get better and better the farther west you go?

Unfortunately, things don’t begin to get really interesting until the umbral phase begins.  The Moon makes first contact with the dark (umbral) part of the Earth’s shadow at 12:45 UT. That’s 7:45 am for me – well after moonset and sunrise, so meaningless. Out in Oregon that’s 4:45 am, so John certainly should be able to see this phase and should see right up to the early stages of totality, though the Moon will be awfully near the horizon then – 6:06 am local time in Oregon and I imagine twilight will certainly impact the drama.

But the folks in Sydney? They get to see the whole show. Totality begins for them at 01:06 am,  Sunday December 11, 2011, with the Moon high in a dark sky.

And yes, if you haven’t figured it out by now, Europe misses this one.

If you would like to get a better handle on what’s going on – or perhaps share this experience with your kids in a meaningful way, I urge you to build my simple Earth-Moon model. I think you’ll find it fun and instructive.

Getting to know – I mean, really know – a planet when you see one

“What’s the bright star in the west right after sunset?”
I guarantee you I’ll get that question more than once in the coming months. I hope it won’t be from someone who has been reading these posts.  The truth of the matter is, we can see only five planets with our naked eye and one of those five is rare – Mercury. You have to know just when and where to look for it. But the other four are pretty darned easy to recognize on sight if you know a little about their habits and looks.
William Tyler Olcott made this clear in his wonderful  little 1907 “A Field Book of the Stars.”  Here is his short  list of rules – each of which you can put to the test any clear night this month:
If the planet is in the west, and very brilliant, it is safe to assume that it is the planet Venus.
If it is brighter than any of the fixed stars, and it is some distance from the Sun, it is doubtless the colossal Jupiter.
If it is very red it will probably be Mars.
Saturn is distinguised because of its pale, steady, yellow light.
OK, let’s  do a few “for examples.” For example, if you go out on the evening of December 26, 2011, about an hour after sunset, and look to the southwest, here’s what you should see.

Click for larger image - Stellarium screen shot.

Yep, that’s dominant Venus less than a fist away from the 2-day-old crescent Moon and both pretty near to where the Sun set an hour ago.  And when you think about it, you’re always going to see Venus somewhere relatively close to the Sun. From our perspective it swings to one side of the Sun for several months, then to the other side of it, since its orbit is closer to the Sun than ours. This coming winter it will get about as far away from the Sun as it can get, before starting to fall back towards it, so this is a good time to watch it – check on its progress from week to week.
What this means is it will frequently be an “evening star” in our western sky – BUT, though Olcott didn’t mention this – it will just as frequently be a “morning star” dominating the eastern sky before sunrise.
Mercury does the same thing – just much faster and it is doesn’t get nearly so brilliant. Last month it was in our western sky, this month it’s in the east before sunrise.
And how about Jupiter? Well, as Olcott wrote: “it is brighter than any of the fixed stars, and it is some distance from the Sun . . .” He also noted that the planets are always found in a relatively narrow arc of sky – the same one that the Sun and Moon follow – I threw the big arrow into this next screen shot to emphasize how the Moon, Venus, and Jupiter are all on the same path – that is, they are all in the plane of our solar system.
So after you locate Venus, swing your head about some to the south and look higher up. Here’s what you should see. This is for December 26, but with the exception of the Moon you should be able to see roughly the same scene any clear evening this month about 45 minutes after sunset. (OK – it will be easier to see the later in the month you look because Venus will be getting higher each night.)

Click image for larger version. This is a modified Stellarium screen shot showing a much larger area of sky than the previous one with just Venus and the Moon.

Mars, Saturn, Mercury and the Moon – a morning event

Now Mars and Saturn are a bit more problematic.  I agree with Olcott’s descriptions, but I also find it hard sometimes to distinguish between a twinkling star and a non-twinkling one that is the visual signature of a planet – and while I can readily identify star colors, they really are just tints and are not all that obvious to the unpracticed eye. Heck, I know some very experienced amateur observers who just don’t see the colors.
But to see what Olcott means, go out just about any morning this month and look to the east about an hour before sunrise.  I’ve chosen the morning of December 22 for a couple of reasons – first, the crescent Moon is in the sky and will help to guide you – and second, this happens to be the longest night of the year – the Winter Solstice, and so it’s a good time to get out and beat the drums and hope the Sun really is going to turn around again this year – stop heading south and start heading back north to chase away the winter doldrums and warm us up.

Aging Moon joins Mercury, Mars, and Saturn in the morning sky - Stellarium screen shot with labels added. Click image for larger version.

A few notes on this image: First, while Mercury is as bright as Mars, this makes it look even brighter – but it really will appear dimmer because it is so close to the horizon and in the morning twilight.  It’s about one fist away from the Moon and less than that above the horizon and will be much easier to spot if you use binoculars.  Saturn and Mars give us a lesson in color.  First, Saturn – kind of yellowish – is right next to the bluest of stars, Spica.  They both would fit in a single binocular field and Saturn is just a tad brighter.

Mars is just a bit brighter, too, and much higher – but don’t expect to see bright red. Fred Schaaf, writing in Sky and Telescope this month, says Mars plainly shows “its striking orange-yellow hue” to the naked eye this month. Yep.  Go back and forth several times between Mars, Saturn, and Spica and you should get the idea of what colors really are like in the sky. Looking at these three objects in binoculars should enhance the color a bit.

Oh – and this is the other end of that arc – the one represented by the arrow in the previous image, showing the way the planets, Sun, and Moon travel on the same path. Here the arrow should stretch from Mercury – near where the Sun will rise, to Mars. When the Sun rises, this is the general path it will follow.

A note about meteors – not this month, but be ready in early January!

The Geminids (December 13-14) are usually a great meteor shower in mid-December, but  this year the Moon will drown out all but the brightest.

However, here’s a heads-up for early January, 2012. Mark January 4, 2012, on your calendar. The rarely seem Quandrantids (I’ve caught them once and not at their best) will peak around 3 am EST on January 4. This is a shower where the peak can be spectacular – 60-200 meteors an hour– but it lasts only a couple of hours. So it’s rare to have the peak come in the early morning hours for your section of the world when the showers radiant is also at or near its highest point and when the Moon offers little or no interference.

For me a fairly bright 10-day-old Moon sets at 2:55 am – weather permitting – and it will be cold, I’m sure – I’ll start watching about 2 am and plan to stick at it until about 5 am – weather permitting.  This, by the way, is a good lesson in how “annual” astronomy events, such as the Quandrantid meteor shower, frequently become “once-in-a-lifetime” opportunities, for this will only happen if the time of the shower’s peak is just right for your location, and if the Moon isn’t interfering – and last, of course, if the local weather cooperates. That’s a lot of “ifs” and it’s why, when you get an opportunity such as this, you shouldn’t pass it up.

Oh – and don’t forget Algol!

I always check the mid-eclipse times for the coming month –  they vary depending on your location. For me the dates and times that look best are:

  • 12/10/2011 @ 08:46 pm
  • 12/13/2011 @ 05:35 pm
  • 12/30/2011 @ 10:30 pm
That means Algol will be at its dimmest for about an hour either side of those times. To make your own checks, go to the Web calculator found here.
For more details on Algol, go here.

Events for April 2010: Venus, Mercury, the Moon, Mars and the Bees, Algol and some morning meteors

The “events” post assumes a new, chronological format this month. The idea is two-fold:

  1. Make it easy to mark your calendars for events worth making special plans to see.
  2. Give you a place to check before going out to observe to see if anything special is happening that night.

There is one category of special events worth checking on, however, that we don’t list here because they’re very specific to where you live and when you observe. These are events involving man-made objects in space – the passages of the International Space Station, Iridium flares, and other bright satellite and space craft passages. There are two excellent ONLINE sources for such events. I urge you to check both, see how they differ, and then make your own decision as to what works best for you.

  • The first is provided by Spaceweather, and you’ll find it by going to their Web site and clicking on the “Satellite Flybys” link on the right, or  by going directly here.
  • The second is the Heavens Above site, and while this requires you to register, the process is painless and free and the result is a lot of information that is specific to your location. You need to know your latitude and longitude, but you can get them by using the link in the “configuration” section near the top of the Heavens Above page. This is a one-time process. Once registered and logged in, study the menu – there’s a wealth of information on satellites and many other things.

April 2010 Astronomical events

Note: While many events are visible throughout the world, the exact time and location in the sky can be dependent upon your latitude and longitude. Since I’m in the mid-northern latitudes (41.5N, 71.1W), specifics, where place-dependent, are calculated for this location.

April 1-15 – Mercury makes what Sky and Telescope calls its “best evening display” of the year, and brilliant Venus will point the way to it. Mercury is brightest at the start of the month and fades significantly by the 15th. But at no time can it hold a candle to Venus, which will be easily found at magnitude -3.9. Just look about a fist or two above the horizon and a tad south of where the Sun set an hour before.

While Mercury is visible to the naked eye and was well-known to ancient observers, it is easiest to find if you use binoculars to pick it out of the twilight. Start half an hour after sunset and locate Venus. In the first few days Mercury will be in the same binocular field with its brighter companion. Here is what the scene should look like on April 1 – no fooling!

From Starry Nights Pro screen shot.

This close relationship holds throughout the 15-day period, though after the first week Mercury starts dropping off towards the north, and by the 13th it may no longer be in the same binocular field – depends on the binoculars used. The 15th is special, though, for Mercury then has a close encounter with a very young Moon. (Scroll down to the listing for the 15th for details.)

April 3 – A very bright, 19-day-old gibbous moon brushes by the bright, red guidepost star Antares at dawn. For me the best time to see this event will be, I believe, between 5:15 and 5:30 am EDT. I’ll be watching in binoculars. The moon will be getting closer and closer, but dawn will be breaking and starting to wash things out. If you live farther west, you’ll see an even closer encounter. Here the separation will be almost a full degree. That is, when viewed with dark skies they will still appear separated by a space greater than the width of the moon itself. The closest approach – about an hour after sunrise for this location – will still leave a gap just about the apparent diameter of the moon itself. I like these close encounters as a reminder of the motion of the moon, which goes counter to the spin of the Earth.

April 14 – The most convenient minima of Algol, the “Demon Star” occurs this month on April 14th at 9:40 pm. Should be fun to check on it about an hour after sunset, then again around 9:40 pm. The only problem – it’s getting very low in the northwest. At 9:40 it will be just 14 degrees above the horizon and will set in a couple of hours – hardly ideal conditions, so I expect this will be the last time I’ll check on it until next fall. For more details on Algol and its eclipses, see the post here.

April 15 – The Venus and Mercury show goes out with a bang, as a 1.4-day-old crescent moon joins them about one fist above the horizon 30 minutes after sunset to the west northwest. Again, Venus should be easy to pick out with the naked eye. Once you have it, use your binoculars and get it in view with them, then move down and to the right just a bit and you should encounter Mercury and the crescent moon. The exact age of the moon and closeness of this encounter will depend on your longitude. From where I sit (41.5 degrees N latitude and 71.1W longitude), the Moon will be just 1.4 days old and less than a degree away from Mercury, which will have dimmed to magnitude 1.5. I don’t expect this to be easy to see. But it all can be visible to the naked eye given an unobstructed western horizon and very clear skies. Once you’ve located it with binoculars, you probably will be able to see it with the naked eye. All depends on a modicum of skill and a lot of luck 😉

Here’s what it should look like.

From Starry Nights Pro screen shot.

April 16-18Mars and the Beehive (M44) mix it up in a delightful pairing for binocular users. Mars has begun its eastward movement against the background stars, and in doing so rolls right between the Beehive cluster and Asellus Borealis, the “Northern Ass.” Actually, this will make a nice binocular grouping from about April 11 to the 23rd, so if the weather doesn’t cooperate on the best nights, try one of the alternatives. I love it when planets get near distinctive stars and star groups because it’s easier then to chart their motions from night to night. So I would urge you to look at Mars with your binoculars at least two nights during this time frame and use the chart below to mark its position. (For other charts to help you locate Mars and the Beehive, see this posting. )

Click image for larger version. Prepared from Starry Nights Pro screen shot.

Download a printer-friendly version of this chart here.

April 22-23 – Greet the dawn with some meteors! Sky and Telescope says these are are the best dates for the Lyrid meteor shower this year. But with the moon offering interference this is a pre-dawn event and the Lyrids seldom put on a big show. If it’s clear, my plans are to be out about 2:30 am. By then the just-past first quarter moon will have set, so it won’t offer interference, and I’ll have a couple of hours before the pre-dawn light begins to wash out the eastern sky. The next night, the Moon will be a bit brighter and sets about 45 minutes later, so there won’t be as much dark-sky observing time available. I like to be aware of this kind of event, but I don’t plan my observing around it. I go out to observe other things and pause once in a while to sit back, look up at the sky for several minutes, and hope I get lucky. Hey – if it’s clear and I can do that, I’m already lucky! 😉

April 24, 25 – Venus and the Pleiades have a relatively close encounter making a nice binoculars view. Actually, they should both fit in the same low-power binocular field from about April 20 to the 28th, but it’s on the 24 and 25 that Venus is closest as it scoots past. The Pleiades are getting closer to the western horizon with each night. Venus is moving in the opposite direction, higher in the sky each night. (It will be our western evening star right into September.) By the 28th it’s about halfway between the Pleiades and the Hyades, though the clusters are getting so low they’re losing much of their luster. Getting back to the 24th and 25th, Venus will be simple to spot. Look for it about an hour after sunset and about one fist above the horizon to the west northwest. Then look for the Pleiades to the northwest of Venus in the same binocular field. Sweeping a little to the southeast of Venus (up and to the left) with your binoculars you should pick up the Hyades and Aldebaran, but not in the same binocular field as Venus.

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