Observing Report: a semi-cloudy night at Joshua Tree

My scope at Joshua Tree Saturday night. Clockwise around the scope are the bright star Capella just in front, the constellation Perseus (12:00), the Pleiades (2:00), the Hyades (V-shaped arrow of stars directly oppose Capella), and Jupiter (4:00). Photo by Kevin Zhao.

Saturday evening I was at Joshua Tree. My summer anatomy students invited London and me along to the Indian Cove campground. I didn’t have room in the car for the big gun so I took my 5” Mak, which is what it’s for—times when I need a decent amount of aperture in a small package. That was no loss: the sky was striped with high, thin clouds all night and never really cleared out. We got decent views of a few things, but the 10” would have been wasted. We used the Mak to look at the Double Cluster and Jupiter. In moments of steady seeing there were quite a few cloud belts showing, and all four Galilean moons were lined up on one side of the planet, which was pretty cool. London brought along his AstroScan and we used it to look at extended objects like the Pleiades and the Andromeda galaxy.

iPhone panorama by Chad Claus. Click for the big version!

The clouds might have made for lousy telescopic views but they made for gorgeous naked-eye skywatching. At sunset the whole sky was striped with light from one horizon to the other.

Here’s another view, actually taken by me for a change. This is the unprocessed raw image, direct from my Coolpix 4500.

Moon halo photo by Kevin Zhao. Jupiter is inside the ring at 1:00, and the Pleiades are outside at about the same angle.

When the moon rose around 11:30, it was surrounded by a ring of faint light. I thought it was a moonbow, but that’s something different. The ring we saw around the moon is called a 22-degree halo and apparently has no other or more poetic name. That’s a shame. In the early morning, when the moon had gotten well above the horizon, it was surrounded by a complete circular halo with radiating clouds on either side. That was worth the clouds. I’ve been under wonderfully clear desert skies many times, but I’ve never seen a moon halo quite like that. For once, I think the clouds were worth it.

Update: There wasn’t just a moon halo, there was also a sun halo Saturday afternoon. Agnes Kwon captured it in pixels. Witness:

Many thanks to Agnes, Chad, and Kevin for letting me illustrate my post with their awesome photos!

The conjunction last Sunday morning

In the latest Mount Baldy observing report I described an awesome predawn conjunction of the moon, Venus, Jupiter, and the bright star Aldebaran. What made it so great was not just the close appearance of four bright objects in the eastern sky, but the almost perfect symmetry of their arrangement: not only did they form an almost perfect arrowhead shape, but the arrowhead pointed straight up toward the Pleiades. All in all, just about the most beautiful celestial sight I’ve seen with my naked eyes.

Just as the kite was flying up over the hill to the east of our observing site, a nice couple drove up and set up a camera. They were Robert and Elizabeth Preston, and they kindly send this photo with permission to post. Trust me, you’re going to want to click through to the big version.

Here’s a closeup of the four conjunction objects from a photo by Terry Nakazono. The moon, Jupiter (top), and Venus (bottom) are all unmodified. I had to crop out the area around Aldebaran (right) and boost the contrast to bring out the star.

I can’t imagine a better end to an observing run.

Don’t miss the moon and planets at sunset this weekend

From bottom to top: the moon, Venus, and Jupiter, on Feb. 24, 2012.

Venus and Jupiter are both high in the evening sky at sunset right now. Just look west right when it gets dark and they’ll be the two brightest stars in the west. Venus is the brighter and lower of the two.

For the next couple of nights they’ll be joined by the waxing crescent moon. Tonight the moon was just below Venus, so the three bodies were stacked up the sky from lowest and brightest to highest and dimmest.

Early next week the moon will pull away from the planets as it continues on its monthly eastward trek around the sky, but Venus and Jupiter will still be there and looking good.

A close-up of the moon at the same time as the photo at top.

Venus is slightly gibbous right now (between 4 and 5 in the diagram below). On March 26 it will achieve its greatest eastern elongation from the sun, 46 degrees, meaning that at sunset it will be halfway between the horizon and the zenith. At that point it will be half-lit as seen from Earth (5). From then on into April and May, Venus will get lower and larger as it goes into its crescent phase (6) and gets ready to pass between the Sun and the Earth. Venus makes that passage all the time as it transitions from being the evening star (east of the sun as seen from Earth = above the western horizon at sunset, 6 in the diagram) to the morning star (west of the sun as seen from Earth = above the eastern horizon at sunrise, 1 in the diagram).

Phases of Venus as seen from Earth

Because the orbits of Earth and Venus are not precisely in the same plane, Venus does not usually pass directly between the sun and the Earth but passes above or below the sun as seen from Earth. This time will be different; as happens only a couple of times per century at most, the orbits are lined up just so and Venus will pass across the face of the sun as seen from Earth. That’s the transit of Venus I’ve been so het up about. Stay tuned for more on that, and keep looking up at sunset for the next few weeks to see Jupiter and Venus continue their tango.

W00t!, W00t!, and Gaaaah!

No time for a real post, so here are a few things of note. Two good, one bad, as the title says.

W00t! #1: Want to have your mind blown? Check out this photographic sky survey “meant to reveal the entire night sky as if it rivaled the brightness of day.” Link.

W00t! #2: Want to see a star blow up? No a simulation, but a real-life supernova? You have two choices: be very patient, or use a telescope. The last 5 naked-eye supernovae in our galaxy were observed in the years 1006, 1054, 1181, 1572, and 1604, although supernova 1987a in the Large Magellanic Cloud, a satellite galaxy of the Milky Way, was also naked-eye visible. Anyway, the point is that if you want to see the light of an exploding star with your own eyes, the best place to observe from is the eyepiece of a telescope. It’s not uncommon for a supernova to briefly outshine its host galaxy–that fact is worth pondering for a moment–and there are literally thousands of galaxies within reach of amateur telescopes, so even a modest telescope will show you supernovae in other galaxies on a semi-regular basis. A good site for keeping track of potentially observable supernovae is this one, which lists them by their visual magnitude (you may also find this limiting magnitude chart and this calculator useful to determine which supernovae are within reach of your instrument).

I bring this up because right now supernova 2011by is at magnitude 12.5 and may get brighter still. It has already been sighted in a 6in telescope (according to a post on Cloudy Nights) and is theoretically observable with even a 3- or 4-inch instrument under very good skies. It’s in the galaxy NGC 3972, which you can find using Stellarium, Cartes du Ciel, or any of a number of other free programs. Right now isn’t the best time to see it, thanks to the nearly-full moon, but hopefully it will still be reasonably bright at new-moon time near the end of the month.

Gaaaah!: Sorry to end on a bummer. The state of California is planning to close 70 state parks for budgetary reasons, and the Salton Sea State Recreation Area is one of those on the chopping block (story here). The Salton Sea is one of my favorite spots for camping and stargazing, and I’m seriously bummed that they’re going to shut down the park. I don’t know who to write to in order to fight this, and even if I did, I doubt if enough people would write to make a difference. One reason I go to the Salton Sea is that it’s a really nice campground that is never empty but never overflowing, either. So it’s a bit of a catch-22: the low traffic that draws me there in the first place pretty well ensures that the park will have few advocates. And I’m not even sure if fighting this would be a good thing. I know that the state can’t afford to keep all of the parks open, and maybe it’s better to shut down a low-traffic place like the Salton Sea park and let the property rest undisturbed*, than to shut down a high-traffic place and drive those folks to the Salton Sea and thereby increase the human footprint. I’ll think about it some more, and look around and see if there is anything to be done. In the meantime, I’m just sad.

*Normally, I’d worry that this was Step 1 in some nefarious plan to sell the land for commercial development, but the Salton Sea is such a commercial black hole that I doubt if such a plan could be put into place even if someone strongly desired it, and there’s no evidence that anyone does. It’s a lonely spot, and that’s the point–I like to get out and enjoy the emptiness.

Globe at Night 2010

We’ve all seen this map. This is why if you’re reading this, chances are better than even that you can’t see the Milky Way at night. For the entirety of human history, everyone everywhere could see more than a thousand stars on a clear dark night. That’s wrecked now, for most of the developed world, thanks to light pollution. And it only took us a couple of generations to do it.

But it would be very easy to unwreck. Our natural heritage in the sky is being washed out by wasted light. Fighting light pollution isn’t about doing away with artificial lighting, it’s about doing away with stupid artificial lighting. Full cutoff bulbs that illuminate roads, sidewalks, parking lots, and front porches contribute very little to light pollution. The problem is unshielded bulbs, which send 50% of their photons up into space. All they’re doing is lighting up the bottoms of birds, bats, airplanes, and satellites. And, not coincidentally, washing out our starscapes.

The bottom line is that unshielded bulbs are wasteful; that’s an awful lot of kilowatt hours we’re sending out into space. Putting a full-cutoff hood on a light doesn’t make it use less energy, but it at least directs all the energy where it’s needed. Or you could use a reflective hood and a bulb that eats half as much power and still achieve the same illumination.

If you want to help fight pollution, there is a very cool project going on now called Globe at Night 2010. All you have to do is go outside, find the constellation Orion, compare your naked-eye view with the GaN magnitude charts, and report your observation using their online form. You can also compare your result with those of thousands of people around the world. If you’re an amateur astronomer, just using the magnitude charts should give you a better idea of how to assess the naked-eye limiting magnitude at your observing site.

Globe at Night 2010 is running from March 3-16, so even if it’s the rainy season where you are, you will hopefully get at least one clear night. It’s fun, it’s easy, you help the human endeavor, and you learn a little something. Go to it!

Mission 15: Ring of Fire

Mission Objectives: Bright Stars, Constellations

Equipment: Naked eye

Required Time: 2 minutes

Related Missions: Three Astronomical Treats for Naked Eyes, Binoculars, and Telescopes

Introduction: It’s a new mission for a new year. New stars are in the skies, and it’s the perfect time to start exploring the heavens–for the first time if you’re new to this, or exploring it again if you’re an old hand. This mission requires no prior knowledge, experience, or equipment; it’s just about getting out and getting acquainted with the night sky.

Instructions: Go outside after dark, face southeast, and find three stars in a straight, vertical line. These are the stars of Orion’s belt. They are flanked on either side by twin bright stars of roughly equal brightness but different color. On the left is Betelgeuse, an enormous red giant that appears yellow to the naked eye. On the right is Rigel, a blue-white supergiant.

Follow the line made by the belt stars down to even brighter Sirius. Sirius is the brightest star in Earthly skies, but it’s a not a giant or supergiant like Betelgeuse and Rigel. In fact, Sirius is a main-sequence star, a little less than twice the diameter of the sun, but about 26 times as bright. By comparison, Rigel is about 40,000 times as bright as the sun. But Rigel is 773 light years away, whereas Sirius is only 8.6 light years from us–the fifth closest stellar system to our own. Sirius, the Dog Star, is the chief star in the constellation Canis Major.

From Sirius, hang a right-angle left turn and head on to Procyon, “before the dog”, so named because it rises just a few minutes before Sirius from mid-northern latitudes. The small and otherwise dim constellation Canis Minor has little else to recommend it, and Procyon serves mainly as a celestial landmark.

Farther left still, and farther up in the sky, are the twins, Castor and Pollux, at the head of the constellation Gemini. If you have trouble keeping them straight, remember that “Castor is close to Capella, but Pollux is in proximity to Procyon”.

Speaking of Capella, it’s the very bright star directly toward the zenith from Castor and Pollux. It’s a brilliant gem in a ring of prominent stars that mark out the constellation Auriga, the Charioteer (this is not the big ring marked in red on the diagram above, but the much smaller blue-white ring on the upper left).

To the right of Capella is Aldebaran, the burning red eye of Taurus, the Bull. Aldebaran means “the follower”, because this star rises after the Pleiades, which it appears to chase from horizon to horizon (to trace that line, see the previous mission). Aldebaran is an orange giant, meaning that it has exhausted the hydrogen in its core and moved off the main sequence. Without the outward pressure of radiation from hydrogen fusion to prop it up, the core of the star is compacting under gravity and heating up. When it gets hot and dense enough to start fusing helium, Aldebaran will bloat into an immense red giant, like its neighbor, Betelgeuse.

And speaking of Betelgeuse, it lies in the middle of the great circle described by Rigel, Sirius, Procyon, Castor and Pollux, Capella, and Aldebaran. I call it the Ring of Fire–nowhere else in the northern sky is there an equal concentration of bright stars.

Below and to the left (east and north) of the Ring of Fire is Mars, which will be at opposition–opposite the sun, and at its closest approach to Earth–in a couple of weeks. The orbit of Mars is more elliptical than that of Earth, and this will not be one of the better oppositions, but it’s still the best look at the red planet that we’ll get for another two years.

What’s next? This mission was just a lightning run through the bright stars of winter. Their respective constellations are packed full of beautiful targets for binoculars and telescopes, and we’ll look at some of those in future missions. If you’re impatient to get started, download this month’s The Evening Sky Map, haul out your optics, and happy hunting!

Mission 14: Three Astronomical Treats for Naked Eyes, Binoculars, and Telescopes

Mission Objectives: Bright Stars, Constellation, Open Cluster, Nebula

Equipment: Free star map, Naked eye, Binoculars, Telescope

Required Time: 10 minutes

Related Missions: Cassiopeia and the Double Cluster

Introduction: I’m in Oklahoma for the holidays. My best observation here so far didn’t require any optical aid at all. Remember last month when I was skunked in my quest to view the young crescent moon within 40 hours of new? On Thursday, December 17, the night after I got into town, I saw the 38-hour-old crescent moon in the western twilight over Oklahoma City, thus fulfilling the last requirement I had left for the Astronomical League‘s Lunar Club. I e-mailed in my completed log sheets on Saturday.

Instead of bringing a little scope with me, I borrowed back the one I had loaned to my brother. It’s a Synta MC90, another 90mm Maksutov-Cassegrain, but unlike my other little Mak it’s a short focal length, widefield scope. I got it out last night to show my nieces the waxing crescent moon, Jupiter, and the Pleiades.

Instructions: Speaking of the Pleiades (M45), they’re one of the best astronomical treats for a clear winter evening. Finding them is easy: look to the east after dark, and find a little knot of stars that looks a bit like a cooking pan. This is not the Little Dipper, although you’d be surprised at how many people think so on first spotting it. If you have a hard time finding the Pleiades, look for the 3/M/W of Cassiopeia, head past the Double Cluster to Perseus, and follow the lower of the two sweeping lines of stars that make up that constellation; the cluster is just off the end of the line. The Pleiades are pretty to the naked eye and probably best in binoculars. All but the widest-field scopes will have a hard time putting the whole cluster in the eyepiece, and even if you manage it, it’s prettier if you can see the cluster as a cluster, with a little open space around it. So this is one of those times that–in my opinion–binoculars trump a telescope.

If you have found the Pleiades, drop straight down (east) to find a V-shaped association of stars. These are the Hyades, another open cluster, in the constellation Taurus. One leg of the V is anchored by a big red giant star, Aldebaran, whose color is obvious even to the naked eye. You can pan around the Hyades with a scope if you like, but the cluster is so big that it really demands binoculars; binos fall right into the sweet spot of putting a lot more stars in your eyes without overly narrowing the view or getting you lost.

From the Pleiades, on to the Hyades, and farther on east you come to Orion, the most magnificent constellation in the sky. Find the three bright stars in a line that form his belt, and then three dimmer stars in another line that form the sword hanging from the belt. The middle of the three stars in the sword is not a single star at all. Rather it is M42,  the Great Nebula in Orion, a vast cloud of gas and dust, dozens of light years across, which is illuminated by the bright young stars burning within.

M42 is what I call a total object: like the moon, it looks good no matter what you use to look at it, and the more you look, the better it gets. With the naked eye, the nebula it is a faintly fuzzy star at the heart of a striking and majestic constellation. With binoculars, you’ll see a bit of nebulosity set amidst the rich starfields of Orion’s sword. In a small telescope, the full glory of the nebula starts to unfold, with glowing streamers of gas and dust spread out like an eagle’s wings. The central star will split apart into a group of four, called the Trapezium. Pour on more aperture and magnification and the view just keeps getting better. If the skies are clear and steady you may pick up a couple more stars in the Trapezium, and the surrounding clouds of gas and dust will start to look like clouds, with delicate knots and swirls.

And on it goes. You are not going to exhaust M42, not in a lifetime of observing. People with telescopes that require large trailers for transport, who have seen M42 literally thousands of times in their observing careers, still gaze into the heart of the nebula for minutes and even hours at a time. The bigger the scope, the darker the skies, the longer you look, the more there is to see.

But, hey, don’t think that if you don’t have a monster scope it’s not worth looking. Remember, M42 is a total object; it looks good at any scale. If the thought of setting up a scope in the cold and dark does not appeal, at least pop outside for a five minute session with binoculars. Make it a present to yourself.

Happy holidays!

Mission 9: The Mote in God’s Eye

Mission Objectives: Bright star, Exoplanet

Equipment: Naked eye

Required Time: 1 minute

Related Missions: Hail to the King

Instructions: Go outside after sunset, face south, and find Jupiter. South and east (or down and left) of Jupiter is a bright star called Fomalhaut. Fomalhaut is the only bright star in that part of the sky, so there’s little chance you’ll confuse it with anything else. It’s not a double star, doesn’t have a striking color, and isn’t part of a striking pattern (it’s also pretty far south, at roughly the same elevation as Sagittarius, so if you’re at high latitudes, good luck). Its attractions are entirely cerebral.

Fomalhaut is special because it has an extrasolar planet, Fomalhaut b, which was the first extrasolar planet to be imaged directly by an optical telescope. What’s all that mean? People had been detecting extrasolar planets for years, by measuring the wobble they induced in their parent stars, or measuring the light drop in their parent stars as the exoplanets pass in front of them, and the spectra of exoplanets had even been obtained, but Fomalhaut b was the first to have its picture taken. The Hubble image itself is cool; it looks like the Eye of Sauron.

Now, as of this writing 405 explanets have been found, with more coming almost every month, especially now that the Kepler telescope is up and running. But most of these orbit stars that are very dim as seen from Earth. Fomalhaut rocks because it’s obvious. You can point it out to someone and say, “That star has a planet, and we have taken pictures of it.”

Hubble image at top from NASA, artist’s reconstruction above from the Joint Astronomy Centre. Apologies to Niven and Pournelle for nicking their title.

Mission 6: Not Everyone’s Pot of Tea

Mission Objectives: Constellation, Globular Cluster, Open Cluster, Nebula

Equipment: Naked eye, Binoculars, Telescope

Required Time: 5 minutes

Related Missions: Eye of the Scorpion

Instructions: Go outside shortly after dark, face south, find Antares, and to the left/east of Scorpio, look for a teapot.

Yes, really. The heart of Sagittarius, allegedly the Archer, looks strikingly like a teapot. Which, I think we can all agree, is a considerably less aggressive incarnation. Once you’ve spotted it, it will be hard to avoid seeing it any time you look toward that part of the sky. It’s especially easy if you can trace Scorpio–it looks like the teapot is about to pour on the scorpion’s tail. Here’s the plain version so you can practice:

Sagittarius is the thick of the summer Milky Way and contains the core of the galaxy. As a result, it is just loaded with deep sky objects (DSOs)–it hosts 15 of the 110 Messier objects, more than any other constellation. It has star clusters in its hair and hanging out of its pockets. Some are open clusters, the result of relatively recent bouts of star formation (“relatively recent” here means “within the last half-billion years or so”), but many are globular clusters or “globs”, spherical micro-galaxies of up to a million stars apiece that orbit the core of the Milky Way in an extended halo.

Sagittarius also has a stunning emission nebula, M8 or the Lagoon Nebula, which is second only to the awesome Orion Nebula (M42) for Northern Hemisphere observers. Like the Orion Nebula, the Lagoon is a site of active star formation; it is lit by the young stars it contains, and more are forming even as you read this (the Lagoon Nebula is only 4100 light years away, and it is highly unlikely that the multi-million-year process of star formation has suddenly stopped since the pyramids went up).

With a clear southern sky and a pair of binoculars–which have hopefully by now been warmed ever so slightly by the brilliant light of Jupiter–you can see three beautiful DSOs that illustrate three stages in the life cycle of stars and of the galaxy itself.

Globular cluster M22 is a fuzzy ball above and to the left of the teapot–I imagine it forming a right angle with the northeastern stars of the teapot lid, as shown above. Through a telescope of less than about 6 inches aperture it will likely remain a fairly fuzzy ball, but pouring on more aperture and magnification will resolve it into something approaching this (image from Wikipedia):

M22 is full of very old main sequence stars, and astronomers estimate its age at about 12 billion years, meaning that it has been around for more than 90% of the history of the universe. Its stars are Population II, which means that they formed shortly after the universe itself, when there had been little time for successive waves of novae and supernovae to seed the universe with heavy elements. No one knows if the Population II stars have planets; if they do, they are probably gas giants and any solid bodies are probably icy and metal-poor. If life arose in this or any globular cluster, it is hard to imagine how any of it could have become starfaring or even radio-using with few or no metals. Nobody knew this back in 1974, when Arecibo sent a “Hey, how are ya?” radio message to the globular cluster M13. M13 was chosen because it is nearby and has tons of stars; somewhat ironically, those stars are the least likely to have civilizations capable of receiving the message or responding (which may be a good thing, if you take a pessimistic view of the likely intentions of technologically superior species).

Closer to us in time of origin is the open cluster M7. It seems to me to form the right wing of an extended kite shape that is otherwise made up of the three stars that form the teapot spout. This bright ball of about 80 stars is about a thousand light years away and its oldest members are about 220 million years old–about 2% the age of those in M22. It is sobering to realize that these cosmic youngsters formed about the time that the first mammals and the first dinosaurs were getting up and running in the Late Triassic Period.

Youngest of all is M8, the aforementioned Lagoon Nebula, which sits right above the spout of the teapot like a tiny puff of steam. In cosmic terms, we’re catching M8 in the act of giving birth. A few tens of millions of years ago it was just another cloud of cosmic flotsam and probably neither bright nor particular pretty. Now it is lit from within, like a paper lantern, by its stellar offspring. In another 200 million years, M8 may look like M7 does today, with all of its ethereal clouds of gas and dust either consumed or blown away by the brash young stars that are even now forming at its heart.

So grab those binos and go see the universe–a stellar nursery (M8), primary school (M7), and retirement community (M22) await. If Jupiter blew your socks off, have a look at M22 and remember that you are looking at stars that are almost three times as old as our solar system. How often do  you get to see something 12 billion years old? Not often, I’ll wager!

…or rather, see these things if you can. There’s a reason that Sagittarius is not everyone’s pot of tea. Like Scorpio, it’s a fairly southerly constellation, which means it never gets very far above the horizon, especially for folks who live up north. Here’s what it looks like from southern England:

So if you’re farther north than about the 40th parallel, you’re probably hosed. You’ll need a clear southern horizon, sans trees, mountains, and especially the light domes of our myriad cities to get a good look. Still, give it a shot–letting the light of 70,000 12-billion-year old stars–photons that have been in transit since the end of the last ice age–fall on your retinas is worth a little effort.

Mission 5: Hail to the King

Mission Objective: Planet, Moons

Equipment: Naked eye, Binoculars, Telescope

Required Time: 5 minutes

Instructions: Look southeast in the early evening and find the intensely bright star!

The ancients recognized several categories of celestial objects: the Sun and Moon, the fixed stars, transitory and unpredictable phenomena from the commonplace (meteors) to the alarming (comets), and a special category of stars that moved in relation to all the others. The Greeks called this last group the planetes asteres (“wandering stars”) or simply planetoi (“wanderers”), and the term survives little changed to this day.

The ancients could see five wandering stars. Mercury, closest in, swings around the Sun every 87 days, and so was identified with the swift messenger of the gods. Venus, the goddess of love, gave her name to the brightest object in the heavens after the Sun and Moon, the morning and evening star. Blood-red Mars was named, appropriately, for the god of war. Saturn, dimmer than Jupiter and traveling more slowly, was named for the Titan Jupiter displaced, the two-faced god of beginnings and of agriculture.

Was it coincidence that the ancients gave the name of the king of gods to the planet that is, in fact, the largest in the solar system? Possibly not. From Jupiter’s long orbital period they probably deduced that it is very distant from Earth, and yet it is the fourth brightest object in the sky, yielding only to the Sun, the Moon, and Venus. Possibly Jupiter’s stately pace through the heavens was thought more seemly for the king of gods than the frantic Sun-centered scurrying of Mercury and Venus (it would have been obvious, then as now, that the two innermost planets never get very far from the Sun).

If you don’t catch Jupiter in the  early evening, don’t fret. It rises near sunset and will be traveling across the southern sky for much of the night. And tonight, Sept. 2, it will be very close to the moon–as it will be again this time next month. (The moon was on the other side of Jupiter last night, but I was too wound up about Mt Wilson to post this then.) That’s an easy twofer whether you’re using binoculars, a small telescope, or the good ole Mark 1 eyeball.

Speaking of binoculars…just for the purposes of this post, I’m going to assume that you’ve either got a scope and know how to use it, or don’t have one and aren’t going to change that by nightfall. We’ll talk about choosing and using telescopes a lot more in the future, but for now I feel that my advice will have maximum impact for people in possession of binoculars. The pool of people who own a pair of binoculars is huge; the fraction of those people who have used them for stargazing is probably tiny. And Jupiter and the moon are the two celestial objects that benefit most from being viewed with binoculars. So here goes.

First off, don’t worry about what kind of binoculars you have. The 10×50 size is most often recommended for stargazing–at 50mm and above, the objective lenses start to really pull in the faint light for chasing star clusters and nebulae. But the Moon and Jupiter are both crazy bright, so light gathering is not the prime consideration. The prime consideration, as always at this blog, is getting out and seeing something you wouldn’t otherwise. (If you don’t have binoculars but want some, consider these).

Second, the view through steady binoculars is a qualitatively different experience than the shaky hand-held view. There are several ways to hold binoculars steady, but the cheapest (i.e., free), fastest, and easiest is just to brace your elbows against something (top of the car works great for me) or to brace the binoculars themselves against something. My first self-conducted astronomical observation, not quite two years ago, was of Jupiter and its moons, using the humble Tasco 7×35 birding binoculars I’d gotten at Wal-Mart back in high school, leaning up against a street lamp to hold the binoculars steady.

What will you see? In even modest binoculars, Jupiter will be a circle, not a point, with between one and four little points of light next to it. The picture above is the simulated binocular view. On one hand, you’re not going to see any detail on the planet. And the four Galilean moons will just be little sparks.

On the other hand–the hand you should be concentrating on–you went to the closet, knocked the dust off whatever binoculars you already had, pointed them at that bright star over there, and now you can see that it is visibly a planet (despite being almost half a billion miles away) and, oh yeah, those little sparks are moons. If you’ve never seen this before with your own eyes, you will have an emotional reaction. Even if you have seen it before, you’ll probably have an emotional reaction. I still do. And usually that reaction is, “Holy BLEEP! That’s BLEEPin’ Jupiter! And its BLEEPin’ moons!” And I want to laugh and cry at the same time, and most of all I want to grab whoever is close and make them look, too. This entire blog is the extension of that feeling.

You want more coolness still? Using only binoculars, you should be able to sketch the positions of the four Galilean moons over several nights (apparently some Italian yahoo dreamt up this diversion like 400 years ago). Drawing in hand, you can open up Stellarium or pick up the current issue of Sky & Telescope or Astronomy and figure out which moon is which. From inside (closest to Jupiter) out, the four biggest moons are Io, Europa, Ganymede, and Callisto. I remember them like this: vowels (I, E) before consonants (G, C), and both sets in reverse alphabetical order.

Alternatively, you can look up the moons’ positions first, quickly commit them to memory (or draw them, or take the magazine or laptop outside with you), and then when you see them in the binoculars you’ll know that that little spark right there is Io, entirely covered in sulphurous volcanoes, or Europa, whose ice-encrusted oceans are the best possibility for finding life elsewhere in the solar system.

As far as I’m concerned, observing Jupiter in binoculars is both a thrill and a blessing. It’s a moving sight, and it can be the basis of a very accessible and very rewarding observing program (like, er, one of these). It only gets better in a telescope. My 90mm Maksutov shows several cloud belts on clear nights, and occasionally the perfectly black, perfectly round pinpoint of a moon shadow transiting the bright face of the planet. My 6-inch reflector shows more bands and more detail, and so on up from there. BUT, as I frequently say, it’s not about the equipment. It’s about the seeing. And Jupiter is one of the best things out there to see.

If you want the fast facts about Jupiter in an attractive, portable, and free format, check out the IYA2009 presentation about Jupiter. It’s part of the upcoming Galilean Nights event on October 22-24, when amateur and professional astronomers all over the world will set up thousands of telescopes to show the general public the wonders of the heavens.

Oh, one more thing: right after sunset, Jupiter is almost directly below Altair. So if you can find Jove, you can find the Summer Triangle, and vice versa. Get after it!