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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.

January 2010 events: Meteors, Mars, and the Moon skims the Pleiades

The Quadrantids are the best meteor shower I’ve never seen!

No kidding. The Quadrantids are tie with December’s Geminids for generating the most number of meteors per hour and will peak on January 3but there are several reasons why I’ve never gotten a good look at them and I’m afraid this year, while giving us a chance to see some, will not be good, particularly for observers in the United States.  That said, I still plan to watch this year. Meanwhile, the  dominant naked-eye planet this month is Mars which gets as close as it will come for the next couple years – and thus will appear dazzling to the naked eye and will appear in the  telescope as big  as it will be until 2013. But I have to be honest – that’s not very big and other years it can get brighter.  What will be fun for observers using the naked eye and binoculars this month will be the Moon skirting the Pleiades,  but –  seems like there’s always a “but” this month – the closest approach will come in the early morning hours.

There also are a couple good chances to catch Algol, the “demon star,” in eclipse this month – no  buts about it – so here’s the line up of some special events for January 2010 with links to the details:


Quadrantid meteors

The good news about the Quadrantids is there are a lot of them! Meteor enthusiast measure intensity of a shower by what is called its ZHR –  Zenith Hourly Rate.  This is a legitimate figure, but significantly higher than what the typical, single observer will see – still, it’s a way to compare apples with apples – or meteor showers with other meteor showers.  The ZHR for the Quadrantids is 120 and only the Geminids have the same high peak.  The popular Perseids, which come in August, peak out at 90, and right now another popular shower, the Leonids, are in a low and expected to have a peak ZHR next november of 15!

So why have I missed the Quadrantids before? Partly because they come in mid-winter when the weather here in New England doesn’t generate much enthusiasm for lying still on your back and looking up at the sky for an hour or two! But also, this is one of those showers that is seen best in the early morning hours because that’s when its radiant point is highest in our sky – and even then the radiant is only about as high as the North Star, so  given the best of circumstances I will miss some. But also this shower has a sharp peak, while some other showers  stay fairly intense for a much longer time span. So you have to hope that sharp peak comes at a time when the radiant is also high in your sky.  In this case – 2010 – that peak comes at 19 hour Universal Time on January 3. That’s  two o’clock in the afternoon for those of us on the East Coast of the United States, hardly the time to observe meteors. What more the moon, bane of meteor watchers because it washes out all but the brightest ones,  will be just a few days past full.

So my plan is this: I will observe starting about 6 pm EST January 3 – when it is fully dark – and going to about 8 pm when the Moon comes up – weather permitting.

Chart from screen shot of Starry Nights Pro software - click for larger image.

The up side to this timing is that  the shower will be at half strength  – according to the “Observer’s Handbook 2010” – for about seven hours either side of its 2 pm EST peak. So I will be in a window when the ZHR might be as high as 60 – very respectable.  However, the radiant will be very low in the northern sky at that point – so low that I’ll miss about half the meteors that are available. (The radiant is near the end of the handle of the Big Dipper.)   Throw in light pollution in that area of my sky and my realistic guess is I’ll see maybe one good Quadrantid every three-to-five minutes.  Still, that’s worth a try.

As with all meteor showers, you need patience and some sort of lounge chair is helpful – and, of course, you need to dress warmly. This is a shower that favors northern observers – the farther north you are, the higher the radiant in your sky.  And as always, the meteors may appear in any section of the sky, but if you trace each backwards you will see it seemed to come from the general area of the radiant point and looking in that general area is a good idea. I’ll focus on the region above and around the North Star.

Oh – meteor showers are usually named for the constellation in which their radiant is located,  but in the case of the quadrantids it was named for a constellation no longer recognized as such.

Mars

This is Mars as seen at it's very close approach in 2003 using the Hubble Space Telescope.

As I mentioned last month, Mars and Earth are closest to one another every 2.1 years – but exactly how close they get each time varies over  a 16-year cycle. So we get close every 2.1 years, but you have to examine each close approach and see where it fits in the 16-year cycle.  This means that some close approaches are much better than others, so the best telescopic views of Mars happens every 16 years! And where are we now in that 16 year cycle? Somewhere near the bottom. But play the hand you’re dealt. If you want the best view of Mars in a backyard telescope, then January and February give you the best chance you’ll have for two years and things won’t start to get really better until about 2014.

On the other hand, if you just enjoy keeping track of the planets with the naked eye, Mars is very easy to find this month. Just go out about four hours after sunset and look for the brightest star in the East. Here are charts for my latitude – 42 degrees north – showing what I will see when looking east, four hours after sunset, on January 1, 15, and 31 respectively. Notice that Mars is higher in the sky as the month goes on? And if you look closely at the pair of stars just to the left (north) of Mars you’ll notice Mars is changing its location relative to the background stars. The changes  you are seeing are a result of the motions of Earth and Mars around the Sun.

Looking east four hours after Sunset, in January from my location in Westport, MA. All charts were made using screen shots from Starry Nights Pro software. I simply added the labels.

Mars will rise earlier each night and be a bit brighter, but even at its brightest will still be outshone by Sirius, the brightest star in our night skies. Sirius is to the right, relative to the charts above, roughly as high in the southeast or south as Mars is in the east. It’s easy to identify because except for the moon, it is the brightest thing in the sky at that time. (Jupiter is brighter, but sets quite early.)

Here are the key numbers and dates for this apparition of Mars, according to Sky and Telescope magazine:

  • Mars will appear larger than 10 seconds in diameter right through March – that’s big enough to see some features in a backyard telescope.
  • In late January it comes closest but will still appear to be only 14.1 arc seconds in diameter at its largest – on a really good year, such as 2018, it will appear to be over 24 seconds in diameter.
  • In 2012 – when we get another close look – it will actually be a tad smaller at its best because it will be a little farther away.

When I get a "good" look at Mars in my telescope I usually see something like this.

What should you be able to see? Frankly, not that much. But it’s still fun to try. With a good telescope and good astronomical “seeing” conditions, you should be able to make out some features on Mars such as the northern polar cap, and large, irregular olive drab splotches that stand out against an orange background. Is this exciting? YES! It really is because you are seeing it live and for me, nothing beats live observing. But it’s also good to have realistic expectations.

Moon and the Pleiades

So the Moon will be  close to the Pleiades on the nights of January 24 and 25 – and real close the morning of January 25, 2010 – so what?

Here’s what.  We usually think of the Moon – and the Sun – as being much larger in our sky than they actually are. When either are near the horizon they look huge. But at any time they are really so small that they can be covered by a finger tip held at arm’s length. In fact, 11 full moons could fit between the two “pointer” stars in the cup of the Big Dipper!  On the other hand, we usually think of the Pleiades as appearing quite small in our sky. But the Pleiades cluster is actually twice as large as the Moon and you can prove this to yourself when you watch the Moon approach this famous star cluster. Seeing them both with your naked eye – or better yet, both in the same binocular or low-power telescope field – is really quite astonishing.  We don’t get this opportunity too often,  so that’s why this event is worth noting. It drives home the fundamental truth that the moon covers just half a degree in our sky – which coincidentally is the same amount that our Sun covers which is why the Moon can eclipse the Sun for us.

The best time to see this is between 4 am and 6 am EST on the morning of January 25.  (The closest approach is at about 11 hours Universal Time, January 25.) That’s when the Moon nearly touches the Pleiades.

Algol in eclipse

I wrote about Algol the “Demon Star” in the posting for October, but it’ s still well placed for viewing January and if you look at the right time, you’ll catch it in mid-eclipse which is cool.  every 2.3 days Algol dims like clockwork, but it is only at its dimmest for about two hours, so to see it in this condition you really need to be watching at the right two hours. Fortunately,t here are several places that will give you a list of times when this occurs – but many of them will be while normal people are sleeping – and many more will be during daylight hours. However, each month there should be one or two dates when it is really a good time for you to catch Algol doing its thing.

Most of the listings I know of for Algol “minima” give date and time in Universal Time. What I like about the one at Sky and Telescope magazine, is it will calculate a list of coming Algol minima for you – and give you the list Universal Time, plus your local time. So it’s easy to glance over it and see when it will be most convenient – weather permitting – for you to take a look. In my case, january 2010 gibes me too such opportunities. The first is January 10, 2010 at  10:32 UT. That translates to 5:32 am January 10 for me in the Eastern Time Zone.  Since I habitually get up early to observe winter mornings, that’s great.  The second opportunity for me comes on January 21, 2010 at  21:49 UT, which translates into 4:49 pm  EST on the same date. That’s right about sunset for me on that particular date, but that’s no problem. It will still be near minimum an hour later as it becomes dark enough for me to see it and the comparison stars. And as the sky continues to darken I can watch Algol slowly get brighter.

You can learn much more about the minima of Algol – and get specific predictions for any date with translations to your local time, but  – by visiting this page at Sky and Telescope.

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