Events April 2014: Mars, the Moon, and the Earth’s Shadow – Yes, a Total Lunar Eclipse !

 

anatomy-of-a-lunar-eclipse-graphic

Love those Lunar eclipses, but who was in charge of the scheduling for this one? Some insomniac like me, no doubt, for on the East Coast of the USA where I live this thing really doesn’t pick up steam until about 2 am April 15, then continues until near when the Moon sets just before dawn. The West coast residents get a somewhat more timely view.

Here’s the schedule for those in the Eastern Daylight Time zone on the morning of April 15:

1:57 am partial eclipse begins

3:06 am totality begins

3:45 am mid-eclipse

4:25 am totality ends

5:33 am partial ends

The Moon sets about the time the Sun rises, which varies according to location. (Eclipses happen at the same time all over the world – but of course what time that is for your location depends on your time zone – and for some, the Moon simply won’t be in your sky during the eclipse hours.  For a complete guide to where this eclipse can be seen and when for your location, see the NASA eclipse pages.

There’s an incredible NASA eclipse Javascript on this page that delivers all sorts of eclipse data and time for anywhere in the world – however, I did notice that the times were  standard – so you need to adjust for daylight savings if relevant.

What adds a special touch to this eclipse is that Mars will be pretty close to the Moon from the time the Moon rises near sunset. I always like watching the fainter stars come out as the Moon goes into total eclipse, then slowly vanish as it comes back. But with this eclipse, Mars will provide a special treat with it’s ruddy hue shining brighter than any of the nearby stars – though Arcturus and Spica will both rival it.  Here’s a chart for my location – the same relationships will apply anywhere, but those farther west will see the orientation of the chart shift since the Moon and stars will be higher in their sky at this point.

 

eclipsed_moon

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

 

The Scorpion should be beautiful on the southern horizon. For me the Moon is about 22 degrees above the southwest horizon at this point. If you have trouble finding it – eclipses vary on how dark they get, then simply look for Mars and Spica – if you get Spica in binoculars the Moon will be in the same field about 2 degrees east of it.

April Planet Parade

Click image for larger view. (Made from screen shot of Starry Nights Pro.)

No, you can’t see the Moon – it’s eclipsed! (Actually, it can be quite red and fairly easy to see – or it can be quite dark and difficult to see during totality. ) Click image for larger view. (Made from screen shot of Starry Nights Pro.)

Jupiter is high in the western sky all month, setting in the wee hours of the morning; by the end of the month it sets closer to midnight, but is still brighter than any star or any other planet in the evening sky.

However, Mars rivals Jupiter, taking over in the eastern sky in the early evening hours and remaining visible all night throughout April. It’s in retrograde motion this month, which means it appears to climb a bit higher in our sky as the month goes on, moving west against the background of stars. This is the best opportunity for two years for telescope users to get a good look at Mars.

Saturn gets high enough to view in the eastern sky about three hours after sunset at the start of the month, and two hours after sunset by the end of the month.

Venus is best seen low in the east about 45 minutes before sunrise, and on April 25th has a nice pairing with the crescent Moon. While Jupiter is brighter than any star, Venus is two magnitudes brighter than Jupiter, so it shows up well even though it is well into morning twilight before it is high enough to see easily. I like finding pretty spots to try to capture the crescent Moon, Venus, and foreground landscape  in twilight.  Here’s a shot I got at the Town Farm in Westport MA when there was a similar  arrangement of the Moon and Venus in March 2014.

venus_moon_farm

Click image for larger view.

 

A Meteor Sprinkle

The annual Lyrids meteor “shower” is not nearly as intense as the Perseids in August or the Geminids in December, but if the night is clear it could be fun. It is supposed to peak (roughly 20 meteors per hour) on April 23 when a  waning crescent Moon will rise after 3 am and start to interfere some.

I must admit that with a shower like this I take it casually. That is, I go out and observe other things, but I keep an eye out for meteors, and if I see one, I try to trace its path backwards to see if it points in the general direction of the constellation Lyra – if it does, I assume it’s part of the shower and not a random meteor. You might see a shower meteor a few days before or after the peak, and it might come at any time of night in any part of the sky, but if I were going to pick an hour to keep a sharp eye out for Lyrids, it would be between 2 am and 3 am on the morning of April 23.

The Lyrids are believed to be remnants of Comet Thatcher, which orbits the Sun about every 415 years.

 

 

Look North in April 2014! See Mizar – the best thing since – well, since sliced bread!

In April the Big Dipper is climbing high overhead in the northeast and starting to pour its contents into the Little Dipper – not a very good idea, but fun to contemplate. Meanwhile, the only double star pair where both stars have proper names – Mizar and Alcor – is high in the northeast and ready to challenge your eyesight and boggle your mind.

Mizar is the middle of the three stars that form the handle of the Big Dipper – the same three that we use as an arc to trace a path to Arcturus. (That reference is explained in this month’s “Look East” post.) Wait until an hour or more after sunset, then focus on that center star. Is it one star – or two? For my old eyes, it is one. And since my eyes are not that bad, I question those who say this is an “easy” test of eyesight. But lots of people do indeed see two stars there when they look carefully. Maybe you’re one of them. If you’re not sure, or can see just one, take a look with your binoculars. Now you certainly should see two.

The brighter of the two is Mizar, the fainter one Alcor. More on that in a minute. First, here’s our northern sky for this month.

Arrows indicate directions in the sky where north is always the direction towards the north celestial pole, and west is always the direction the stars appear to move. Click image for larger view. (Developed from Starry Nights Pro screen shot.)

Download a printer-friendly version of this chart here.

And here’s what you should see when you look with binoculars at the Big Dipper’s handle.

Zooming in on the center star in the Big Dipper’s handle using binoculars, you should see it is really two stars – Mizar and Alcor. Click image for larger view. (Developed from Starry Nights Pro screen shot.)

The words “double star” simply mean that a star that appears as one to our naked eyes, is seen as two when optical aid is used. But they may simply be two stars that are closely aligned, yet in reality very far apart and have no real connection to one another. “Binary star” is the term used for two stars that are gravitationally linked to one another. So here’s the double rub with Mizar:

  • When you are looking at Mizar and Alcor, you probably are looking at six stars, not two!
  • Scientists still dispute whether Mizar and Alcor are a true double, even though they have been observing this system with telescopes since 1650!

My “sliced bread” reference figures into the Mizar/Alcor picture in a roundabout way. I have trouble remembering things. So when I wanted to remember the approximate distance to Mizar – 80 light years – I asked myself what interesting thing was going on 80 years ago that can help me remember the distance to these stars? And the answer – given a little research – was that about 80 years ago America was introduced to sliced bread all packaged neatly. Actually, sliced bread was first introduced in 1928, according to Wikipedia, but it was in 1930 that the first national marketing campaign began for “Wonder Bread.” Wonderful. So about 80 years ago the light you see left Mizar and Alcor to begin its journey to your eye.  Don’t let the different dates bother you because an approximation is close enough.

And Mizar alone is a lot more interesting than sliced bread.

Even a small telescope reveals that Mizar itself is a beautiful double! That’s what was revealed when a telescope was turned on it in 1650. But no telescope can reveal to the eye that these two stars are in fact, each a double! The stars in each pair are so close to one another that only an instrument known as an interferometer can reveal them. So what we see as Mizar is in fact four stars. (Double stars are a special love of mine, and I wrote about observing Mizar  in the double star blog I share with John Nanson here.)

But what about Alcor? The Hipparchos satellite, the best modern source for star distances, found Mizar to be 78.1 light years away and Alcor to be 81.1. Those are great ball park figures and good enough for the sliced bread reference. But they may be wrong. The astronomer James Kaler wrote a few years ago in his book “The Hundred Greatest Stars” that these distances may be wrong – in fact, some evidence suggested then that Mizar was actually farther away than Alcor. Kaler concluded in his book that they are “probably paired.”

But now comes more evidence as reported in the current (2014) Wikipedia reference to Mizar:

. . .In 2009, it was independently reported by two groups of astronomers (Eric Mamajek et al., and Zimmerman et al.) that Alcor actually is itself a binary, consisting of Alcor A and Alcor B (a red dwarf star), and that this binary system is most likely gravitationally bound to Mizar, bringing the full count of stars in this complex system to six.

So what our naked eye reveals as one or two stars, may indeed be a complex system of six stars! Which in my mind says that slicing up Mizar and Alcor this way may be – well, may be the best thing since sliced bread and just the sort of thing that makes observing the stars such a treat for the eye and mind!

Look East in April 2014 – take a simple slide to the World’s Fair Star and bump into Mars as a bonus!

 

uhhh

The name”Arcturus” derives from Ancient Greek and means “Guardian of the Bear.” It is the brightest star in the constellation Boötes. Click image for a much larger version. (Prepared from Starry Nights Pro screen shot.)

 

Click here to download a printer-friendly version of the above chart.

Arcturus isn’t universally known as the “World’s Fair Star,”  but  it should be.  Its light bridged two World’s Fairs, making an astronomical link between the one in 1893  and a second in 1933 – both held in Chicago.  It’s intriguing that  the general public was excited enough about science – in the middle of the Great Depression – to make such a link attractive to the Fair’s promoters. Light from Arcturus  - believed at that time to be 40 light years away – was captured by the 40-inch refractor at Yerkes Observatory and its energy used to turn on the lights for the 1933 Fair.

This put the public spotlight not only on Arcturus, but it raised consciousness about the vast distance between us and that star, since the light being used had started its journey during the 1893 Fair and arrived just in time to start the next Fair. When you know light can circle the Earth more than seven times in a single second, you start to understand just what an incredible journey that was.

Of course Arcturus has many other distinctions. For one thing, it makes a perfect connection with the best known asterism in the sky, the Big Dipper.  To find it, all you have to remember is “follow the arc to Arcturus.

And in 2014 you get a bonus – keep following that arc and you’ll quickly come toa slightly brighter “star,” the planet Mars! More about that in our “events” post for April, but I did add Mars to this month’s “look east” chart. It forms a nice triangle with Arcturus and Spica, another bright star we’ll meet next month as it’s quite low this month.

Getting back to Arcturus – another way to remember where to find Arcturus is its name, derived from ancient Greek, which can be translated as “Bear Watcher.”  That’s because Arcturus looks like it’s keeping an eye on the “Great Bear,” Ursa Major, as both circle the northern pole.

You can also think of the magnitude system by which we rate the brightness of stars as starting near Arcturus. At magnitude minus .04 it’s about as close to zero as you can get – the minus sign indicating it is a tad brighter than zero.  Its absolute magnitude is also pretty close to zero since absolute magnitude is defined as how bright a star would be if it were about 33 light years from us, and by modern measurement Arcturus is now believed to be about 37.6 light years from us.  That makes its absolute magnitude -.29.

Arcturus has the distinction of being the brightest star in the northern celestial hemisphere, but this is splitting hairs in several ways. It means it’s the brightest star north of the celestial equator. Sirius, now over in the southwest, is obviously  brighter. But Sirius is south of the celestial equator. Both stars are located close enough to the celestial equator so they can be seen from most places on Earth.

It’s interesting to note, however, that Mars is outshining it this month- by quite a bit. In round numbers, Arcturus is zero, Mars is minus 1.2 and Sirius, setting in the est early on April evenings, is minus 1.5.

But Arcturus (-.04) also wins the “brightest star in the northern hemisphere” distinction by another hair. Remember that the lower the magnitude number, the brighter the star. Both Vega (.03) and Capella (.08) are north of the celestial equator, and the difference in brightness between Arcturus (-.04), Vega (.03), and Capella (.08) is roughly a tenth of a magnitude.  For practical purposes, they all look the same.  But in practical terms, making the comparison by naked eye is – well –  very impractical. Capella is currently fairly high in the northwest. But next month, when Vega is high enough in the east to see well,  Capella will be rather low in the northwest. At that time Arcturus should look brighter – but its actual brightness will be aided by the fact that it is high over head at that time, so you are seeing it while looking through a lot less air than you will be when looking at Vega or Capella. Besides, visually trying to compare stars that are this far apart in our sky is next to impossible since you have to look away from one to see the other. I simply think of all three as magnitude zero and leave the hair splitting to the scientists and their instruments.

Oops – we interrupt this program for a bulletin from 1907!

Yes, having just written how impractical the naked eye comparison is, I found this passage in “The Friendly Stars” by Martha Evans Martin, a book that was published more than a century ago:

Arcturus and Capella are so nearly equal in brightness that astronomers differ as to which outranks the other, even when they measure  their light with a supposedly accurate  instrument and a trained eye. To my own eye Arcturus outshines Capella, and on asking various inexperienced persons for off-hand opinions as to the relative brightness of the two stars, I have invariably had an answer in favor of Arcturus. The best authorities, however, make Capella a shade brighter.

Oh my! And now with 100 years of scientific progress, the verdict is that Martha Evans Martin and her causal observer friends were correct – and the “best authorities”  wrong. Arcturus is the brightest.  So much for my idea that you can’t tell the difference with the naked eye! Give it a try and see what you think. (You can find a chart for Capella and more details about that star  in this post.) Since we’re ranking stars, however, Arcturus is actually fourth on the list of brightest stars – two others that are ahead of it, Canopus and Rigel Kentaurus, are not seen by observers in mid-northern latitudes. Sirius, of course, is.

While Arcturus radiates a lot of energy, much of it is not in the form of visible light. It has what’s known as a “peculiar spectrum” and radiates much of its energy in the infrared portion of the spectrum.  This means that to our eyes it doesn’t look as bright as it really is.

Orange-ish Arcturus is 215 times as bright as our Sun and 25 times the Sun’s diameter. (Image courtesy of  Windows of the Universe.)

One more deception of sorts: This brightness is not because Arcturus is so big – well , yes it is, but not big in terms of the amount of stuff in it, but big in terms of surface area. If you’re measuring the amount of stuff that makes up Arcturus – its mass – it is about the same size as our Sun. But Arcturus has a much greater surface area, so think of it as a hugely bloated version of our Sun. (Keep that in mind when you look at the comparison sketch above.) It is a much older star and is now going through its red giant phase, something our Sun will probably do several billion years from now, burning the Earth to a cinder in the process.

Hmmm . . . to get an idea of how much impact that large surface area has, if you put our Sun out near Arcturus it would be barely visible to the naked eye – and then under truly dark –  not light polluted – skies.

Vital stats for Arcturus, also  known as Alpha Bootes:

•    Brilliance: Magnitude  -.04, brightest star in the celestial northern hemisphere; shines with the luminosity of 215 Suns.

•    Distance: 37 light years

•    Spectral Type: K1 Giant

•    Position: 14h:15m:38s, +19°:10′:5

Guideposts reminder

Each month you’re encouraged to learn the new “guidepost” stars and asterisms rising in the east about an hour after sunset. One reason for doing this is so you can then see how they move in the following months. So if you have been following – even if this is just your second month – look for the previous guidepost stars and asterisms that you have learned and that are still with us in April. Here’s the list from east to west.

  • Arcturus
  • Leo’s Rump  (triangle)
  • The Sickle
  • Regulus
  • the Beehive
  • Procyon
  • Sirius
  • Pollux
  • Castor
  • Betelegeuse
  • Orion’s Belt
  • Rigel
  • Capella
  • the Kite
  • Aldebaran
  • the Winter Hexagon
  • the Pleiades 

Events for March 2014: Planet Sandwich Seasoned with a Sprinkling of Zodiacal Dust

Two realities - The image above gives you an idea of the true size and look of the planets visible in March skies. (From left, Venus, Earth, Mars, Jupiter, Saturn) That's one reality. What you see with your naked eye looks like stars - though very bright ones.

Two realities – The image above gives you an idea of the true size and look of the planets visible in March skies. (From left, Venus, Earth, Mars, Jupiter, Saturn) That’s one reality. What you see with your naked eye is much different.  Planets look like stars – though very bright ones  and some with distinctive hues.

At dusk Jupiter dominates the night sky high overhead –  think of it as one slice of bread for our sandwich. During morning twilight Venus dominates the sky low in the east – that’s the other slice. Between we have Mars on the evening side of midnight and Saturn on the morning side of midnight.

The “seasoning” – Zodiacal Light  - is interplanetary dust that forms a soft cone of light rising out of the west about 80 minutes after sunset – but is only visible if your skies are dark enough.

In total this makes a tasty show at any time of night to supplement the annual,  ever-advancing march of the stars. Here’s where and when to look.

The Zodiacal Light is the most challenging and can’t compete with the Moon’s light, so it’s available for the first two nights of the month, then comes into view again starting on the 18th and going for the rest of March, 2014.  To see it you need a clear sky to the west with no light pollution in that direction. You also need to allow your eyes to dark adapt. for 20 minutes. What you’re looking for is something roughly akin to the Milky Way in brightness, but in a soft pyramid shape that starts out wide as it rises from the horizon and leans to the south as it reaches one-third or more up the sky in the general direction of Jupiter. It’s really quite an amazing feature.

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! In the light of that information, it’s absolutely awesome if you see any thing at all!

Jupiter dominates the stars of Gemini, including the two bright twins to the left, Castor and Pollux.  In the midst of the brightest stars in our skies - the Winter Hexagon - it is the brightest of them all.

Highly recommended that you click this image for larger version. Hard to see the stars otherwise.

Jupiter  is on top these March nights, sharing the same general area of sky as the Gemini Twins. I took the picture (above) of it in late February – it’s position in March won’t change much, though it will get a little dimmer, it will still be much brighter than any star. As always, it’s fun to see if you can hold your binoculars steady enough to detect one of its four largest Moons. When it’s high like this you’re looking through less air and they may be easier to spot – but then, it’s a  bit hard on the neck to look so high in the sky while holding binoculars.

Again. to see any of Jupiter’s Moons your eyes have to be dark adapted, its best to use the largest, most powerful binoculars you can hold, such as 10X50, and you need an idea what to expect. The moons will be roughly in line with Jupiter’s equator – but at any given moment the number visible will vary, as will their distance from the planet, and which side they may be on. (They can all be on one side, they can be split two to a side, etc.) Jupiter together with its Moon – even when they are most distant, are only going to take up about 1/20th of the typical binocular field.

Here’s the sort of thing you are hoping to see:

How Jupiter’s moon might appear at one specific moment – in this case a moment when they were all on the same side of the planet. Of course the next night the view could be quite different. The letters stand for Europa, Io, Ganymede, and Callisto.

If this is your first time looking for the moons, do yourself a favor. Go to this page at the Sky and Telescope Web site and open the JavaScipt utility. It will tell you right where the moons are – and which is which – for any given moment.

As Jupiter dims a bit during the month, Mars becomes quite bright reaching magnitude -1.3 by the end of the month, and shines with a distinctive reddish hue. That’s  almost as bright as Sirius, but is no challenge to Jupiter, both of which appear white.

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

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

It rises about 3.5 hours after Sunset at the start of the month, but comes up during evening twilight at the end of the month. Generally it will be well placed for naked eye observing about an hour after it rises – those with small telescopes may want to wait another hour or two for a better view. That’s why I see it primarily as a late evening object.

You’ll find it by looking to the east about four hours after sunset as March begins. The Big Dipper will be high in the northeast. Follow the curve of it’s handle down to the bright star Arcturus. Continue this curve and you will come to Mars, roughly five degrees from the bright blue star, Spica. (Remember: When low on the horizon bright stars and planets will appear to sparkle and change color because you are looking through so much air.) While these relationships will remain the same, as the month goes on Mars will be rising earlier and earlier.

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

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

Saturn still is best seen in the early morning hours, though it rises just before midnight in the southeast. I think the best guide to it is the triangle it forms with Arcturus and Mars. Of the three corners of this triangle, Saturn is dimmest, shining with a soft yellowish light. However, it still outshines the stars in its vicinity.

You can’t miss Venus if you’re up an hour before sunrise. It actually comes up a couple hours before sunrise and in morning twilight is well above the southeast horizon an hour before sunrise. At about magnitude -4.7 (it gets a bit dimmer towards the end of March) it simply outshines everything except the Sun and Moon, so there’s no mistaking it and no difficulty finding it. Just look in the right general direction at the right time.

On March 27, 2014 a very thin, waning crescent Moon should fit in the same binocular field with Venus roughly three degrees up and to the left.

Look North in March 2014 – Oops, there’s a big hole in the sky!

Well, not really – but unless you live in an area with very dark skies, free of light pollution, you’re going to have a hard time seeing the faint stars above Polaris, the North Star, at this time of year. Here’s what our March north sky star chart looks like.

Our northern sky is quite dark above Polaris, but the Big Dipper is prominent in the northeast and serves as our primary guide to finding the North Star. Click image for larger view. (Prepared from a screen shot of Starry Nights software.)

Click here to download a printer-friendly version of this chart.

Notice the emptiness? The area labeled “Dark Hole?” Mind you, this is not a black hole – just an area of our sky that looks quite empty – unless your viewing location is free of light pollution and your eyes are thoroughly dark adapted. If you can see all seven stars of the Little Dipper, then you should see several stars in this area. But even then I doubt if you will be able to trace out the constellation which goes there. It’s known as Camelopardalis. My copy of Urania’s Mirror, published in 1832, says Camelopardalis consists:

. . . of 58 stars, but none larger than the fourth magnitude. . . .The Camelopard is an Abysinian animal, taller than the elephant, but not so thick. He is so named because he has a head and neck like a camel, and is spotted like a leopard; but his spots are white upon a reddish brown ground. The Italians call him giraffa. To Hevelius, who formed the constellation, he owes his celestial honors.

Ah, giraffe! Thank you, Italians. Here’s how he is pictured in full color on one of the constellation cards that came with Urania’s Mirror (The scan is © Ian Ridpath.)

Camelopardalis as depicted on the card from Urania’s Mirror, 1832. Notice the Pointer Stars of the Big Dipper are near the upper left and Polaris is just to the right of the giraffe’s head, so at this time of year the giraffe would appear upside down in our northern skies.

If you put him in the sky at this time of year his head would be down near Polaris. . . . Hmmm… the illustrator seems to have forgotten the spots mentioned in the text, and the animal’s neck got a bit longer than a camel’s. Ah well – while the 1830s had some advantages in terms of simplicity, I don’t think I would like to be trying to learn the night sky with Urania’s Mirror as my only guide.

Oh – but speaking of long necks, one of the things that has always fascinated me is some of the early attempts at astronomical telescopes and particularly the one in the following woodcut. This was an instrument built by Johann Hevelius in the mid-17th century at his observatory in Poland. The tube was about 150 feet long – befitting, in a strange way, for the man who put a giraffe in the northern sky!

Click image for larger view.
There was a logic to this giraffe-like telescope.
At the time a telescope’s lens could not bring the different colors of light to a single focus, so bright objects were always fringed with color and nothing was in really sharp focus. This negative effect, however, could be lessened by making the telescope’s focal length longer – so to get a really good telescope you had to go to these ridiculous extremes – which, of course, made it a nearly impossible telescope to use in any practical way.
Impressive to look at – difficult to aim and look through.
Fortunately the achromatic lens – combining two different types of glass – was invented and this reduced the problem considerably even in a relatively short telescope. We still use such achromatic lenses today ins mall refractor, though if you want to get a really sharp, color-free image you pay considerably more money for an apochromatic lens. Or, you listen to Newton who figured way back int he 1600s that the way around this was to design a telescope that used a mirror to collect the light rather than a lens. Trouble was, it took a long time to learn how to make mirrors that didn’t tarnish quickly when exposed to the night air. Nothings easy!
Now – about or “hole” in the northern sky. Get to a place where light pollution is at a minimum and it will fill with stars – relatively faint, but they are there. Just scan around with binoculars and you’ll find some even through the typical light pollution most people today are forced to endure. 

Look East: March 2014 Roars in like a sickle and triangle! (Huh?)

Sure, I’d like to tell you March roars in like a lion – but honestly it’s easier to point to the sickle and the triangle and the “Little King” we call Regulus, this last being the new guidepost star for March. But there is a lion there, too. Let’s look at the sickle and triangle first, though, because they’re two very easy asterisms you’ll see in the east about an hour or so after sunset. The Big Dipper off to the northeast gives you an idea of size for comparison – and the same pointer stars you use inthe DIpper to point to the north star – they can be used to point inthe opposite direction where they come very close to Regulus, about 45 degrees away.

This is the eastern sky as it will appear about an hour after sunset from mid-northern latitudes. Click image for larger view. Prepared from Starry Nights Pro screen shot.

This is the eastern sky as it will appear about an hour after sunset from mid-northern latitudes. Click image for larger view. Prepared from Starry Nights Pro screen shot.

Click for printer friendly version of the above chart.

OK – so can you make this into a lion? I find it fairly easy if I consider the sickle his head and mane – and I consider the triangle his rear haunches. I leave the rest to my imagination and don’t really attempt to connect the dots.

Leo does look much like the Lion depicted inthe 1603 Bayer catalog.  Click image for larger version.

The stars of Leo do indeed trace out some key parts of the Lion depicted in this plate from the 1603 Bayer atlas. (Click image for larger view.) Note that the bright star that marks the tail is named “Denobola,” which in Arabic really does mean “tail.” We encounter this also in the tail of Cygnus the Swan where the bright star is named “Deneb.” The Arabic star names are frequently descriptive. (Image courtesy of Linda Hall library of Science, Engineering and Technology.)

Regulus, our new bright guidepost star for this month, means “little king,” or “prince,” in Latin. That fits right in with the lion‘s reputation as King of the Beasts. And what a lovely image to have a prince leading a lion onto the night-time stage this month!

Is Regulus memorable in its own right? Well yes. It’s a star that is spinning so fast that if we could see its disc, it would look like a beach ball that someone sat on. It takes Regulus about 16 hours to make one rotation – in comparison, our Sun, a smaller star, takes about a month to rotate. In fact, if Regulus were spinning just a bit faster, it would spin itself apart!

The rapid spinning gives Regulus an equatorial diameter that is about one-third bigger than its polar diameter. This also results in the polar regions of Regulus being much hotter than its equator.

Regulus is also a multiple star system, but as such rather dull visually. The second star in the system is much fainter, so it can barely be detected by a skilled observer using binoculars – and in a telescope it’s so far away from the primary star that the two stars don’t seem like a pair at all. Both these stars are spectroscopic doubles – meaning the companions are so close we can’t see them with a telescope.

Though a relatively young star – about 250 million years as compared to the five-billion-year age of our Sun – Regulus is apparently nearing the end of its normal life as a “main sequence” star. That is, it’s about to finish burning hydrogen, which means it will soon go into the last stages of its life. But according to Jim Kaler, Regulus is also a curious case. It appears to have a very close white dwarf companion which scientists believe once was much larger and brighter than Regulus. But the gases were drawn from the white dwarf into Regulus, making Regulus both huge and bright and causing it to spin the way it does.

In total, Regulus is another example of how what looks like a common star to us, is quite fascinating when seen in the light of modern science.

Vital stats for Regulus:

• Brilliance: Magnitude 1.35, 22nd among the brightest stars in our sky; shines with the luminosity of about 150 Suns.
• Distance: 77 light years
• Spectral Type: B7V
• Position: 10h:08m:22s, +11°:58′:02

The buzz about the Beehive (M44) and Leo’s whiskers – a binocular treat!

In ancient times the constellation Leo extended much farther east and west, and M44 was considered to be its whiskers.

from “The Next Step – Finding and Viewing Messier Object” by Ken Graun

Whiskers indeed! I like that. It’s a great way to remember where to look for M44, for if you can find the Sickle – the huge head and mane of Leo – then all you have to think is “now where would his whiskers be?” Scan 2-3 binocular fields in that direction – westward – and you should soon stumble upon M44, the Beehive. Here is a chart you can use to find it. Do wait  until about two hours after sunset when it is really dark and M44 is well up in the sky.

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

Click here to download a black-on-white (printer-friendly) version of this chart.

M44 also is known as “the Beehive,” and Praesepe, which is Latin for manger. And if you have dark skies, away from light pollution, you will see this as a small, wispy cloud, perhaps suggestive of Leo’s whiskers. It is, in fact, a beautiful star cluster as binoculars or a small telescope will reveal. Galileo first discovered its true nature, and in this hazy patch counted more than 40 stars. You should see about that many with your binoculars. This is one of the nearest star clusters to us, and although there is still debate over its exact distance, it is around 580 light years. That compares with about 400 light years for the Pleiades. The two clusters are pretty close to the same size, but M44 is considered much older. M45 – the Pleiades – is estimated to be 78 million years old, while M44 is thought to be about 660 million years old. As star ages go, they’re both quite young. But open clusters, such as these, do not last too long – the members stars tend to get drawn off by close encounters with other stars as the whole clusters moves about our Milky Way galaxy.

The Latin name, Praesepe, is worth examining because it explains the names of two relatively bright stars which flank it – Asellus Borealis and Asellus Australis. Borealis means “northern” and Australis means “southern.” Asellus means “ass” – as in donkey – and Praesepe means “crib” or “manger.” In other words, the Beehive apparently looked to some like a pile of hay in a manger, and these two flanking stars were donkeys eating that hay, one to the north and one to the south. In binoculars the scene should look something like this.

M44 and surroundings as it would appear in binoculars with a 5-degree field of view. Click image for larger view. (Chart derived from Starry Nights software screen shot.)

Click here to download a printer-friendly version of this chart.

The two donkeys are about as bright as the stars in the handle of the Little Dipper, so under dark skies should be faintly visible to the naked eye with the northern one the dimmest. The third star, Eta Cancri, is dimmer still. Its name, however, indicates that it, the Beehive, and other stars shown here are all part of the rather obscure constellation known as Cancer, the crab.

February 2014 Events: Obvious Jupiter, Morning Venus, Subtle Zodiacal and a timely wink from the Demon

Yep, you can’t miss Jupiter this month.  It’s well up in the eastern sky as it gets dark and brighter, by far, than even Sirius, the brightest star we folks in the north see.

What other special events are on parade this month? Well, the Moon provides a wonderful viewing – or photo op -with Venus in the predawn sky late in the month; the last two weeks of February will be a good time to look for that elusive Zodiacal Light about 80 minutes after Sunset, and if the weather on February 17 cooperates, we have a perfectly timed eclipse of Algol, the Demon Star, for folks in the Eastern Half of the US. ( There are other dates with the Demon available too for other parts of the world.)

So let’s start with Jupiter. You really can’t miss it even if you’re a beginner. In fact, if you’re a beginner this is a good time to let Jupiter be your guide to the Winter Hexagon. As mentioned in our “look east” post, you’ll find it in Gemini. Look to the southeast a couple of hours after sunset and here’s what you should see.

Click image for much larger version. To get the full beauty of this section of sky find an area with a clear horizon to the southeast and go out on a February evening a couple of hours after sunset. The chart shows what you'll see. The link below provides a small black-on-white version you can print and take into the field. (Prepared from a Stellarium screen shot.)

Click image for much larger version. To get the full beauty of this section of sky find an area with a clear horizon to the southeast and go out on a February evening a couple of hours after sunset. The chart shows what you’ll see. The link below provides a small black-on-white version you can print and take into the field. (Prepared from a Stellarium screen shot.)

Click here for a printable map of the above chart.

Jupiter reaches its highest point as it crosses to the south about 5 hours after sunset near the start of the month and closer to three hours after sunset at the end of the month. As the chart shows, Sirius will be lower and more to the south.

Moon and Venus team up for a Picture Perfect  Pre-dawn Sight

Venus is a morning star and really stays pretty close to the Sun this month, but as Sky and Telescope points out, there’s a great meeting of Venus and a thin crescent Moon on the morning of February 26. Here’s what to look for then.

Click picture for larger version.

Circle shows the typical view through ordinary binoculars – you may just be able to fit them both in the same field of view. Click picture for larger version.

Soft, elusive, and fascinating – Zodiacal Light

Mornings not your thing? Well from February 16 to March 2 the Moon will stay out of your way if you go out about 80 minutes after sunset and look for the elusive, zodiacal light. This is faint – sort of like the Milky Way – but its a pyramid of light rising up from where the Sun sets and going roughly halfway up the sky and leaning to the south.  To see it you must have dark skies pretty much free of light pollution. (A city to your west, for example, would likely ruin it.) And, of course, your eyes must be dark adapted.

Still, it’s a fascinating cloud of fine dust. Here’s what I said about it a couple of years ago – and it still applies:

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 Moon. So you want to wait until a few days after full Moon to begin this quest. I feel I have a good shot at it from my favorite ocean-front observing point where I have a clear horizon to the west with no cities to create light domes there. Evenings in February and March – and mornings in September and October – are the best time 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  roughly 80 minutes after sunset. You can check for an exact time for your location by getting information from here on when astronomical twilight ends. (The drop-down menu on that page specifies the times for astronomical twilight.) As astronomical twilight ends you want to start looking. As with any faint object, your eyes need to be dark adapted, so I am assuming you have been out for at least 15 minutes with no white light to dazzle you. If you try to look for this earlier, you may confuse it with twilight. Much later and it is not as bright, for 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!

Now, about that Demon!

I wrote about Algol the “Demon Star” in this  posting for October, but it’ s still well placed for viewing in February, and if you look at the right time, you’ll catch it in mid-eclipse, which is cool. For those on the East Coast, the most convenient time will be roughly 7:45 pm. Technically, the eclipse goes on for about two hours with the lowest point – the star at its dimmest – at 8:44 pm EST.  But to appreciate this you should check it an hour before to see the normal brightness, then look again at 8:44 pm. Of course, you could start at 8:44 pm and note how it brightens during the next hours. Either way, it will convey why ancient star gazers considered this the “Demon Star.” These events happen often enough for them to notice it dimming every once in a while – sort of winking at them – and no other bright star does that, so it’s easy to imagine the stories that would be told.

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, there are several places that will give you a list of times when this occurs – but many of these times 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 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, February 2014 gives me a couple of opportunities worth noting:

  • 02/14/2014 @ 11:55 pm
  • 02/17/2014 @ 08:44 pm

With winter weather it’s easy to get clouded out, so the more opportunities the better your chance of seeing something. I find these eclipses amazingly elusive and rarely see one, maybe because I think there’s always going to be another opportunity – and there will, but . . .

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