Starry Night 7: Streaming Data On-Demand

Starry Night Pro Plus 6, when fully installed, occupied more than 10GBs of disk space. The sheer size of it required jumping through lots of technological hoops; from huge downloads to special DVDs, each with their own set of gotchas. This led to a lot of problems, all to deliver every last bit of data, much of which might never be accessed!

With the ever expanding volumes of interesting astronomical data available to the general public, as well as the near ubiquitous availability of high-speed internet access, Starry Night 7 was designed with a new mantra... deliver it on-demand!

Not wanting to sacrifice our tradition of beautifully simulating huge sets of astronomical data, we designed a new, robust system to stream the high-resolution, or rarely accessed data as its needed.

Not only do we now have the ability to deliver you, our users, essentially infinite amounts of astronomical data, but we can now deliver you ONLY that data which you want.

The system, at its base, is quite simple:

Zoom in on a particular piece of the sky, descend onto Mars, or choose one of dozens of available horizon panoramas and Starry Night checks your local hard disk for the necessary files. If they're found, they're loaded into the sky. If not, Starry Night makes a request to our servers to download the necessary data, streaming it to your computer where it will remain for the next time you need it.

This was done in a very limited way in Starry Night 6... only very dim USNO stars were served up by this system.

We have since expanded on that (and will continue to expand on that) to include the AllSkyImage layer and dozens of high-resolution planet surface textures. Horizon Panoramas are next to come along with individual object data, and more and deeper databases.

Some 27 GBs of data rests on our servers, waiting to be streamed! Sit back, zoom in, and enjoy!

Starry Night 7.0.2 and Beyond

Development of Starry Night 7 is proceeding quickly, so I thought I'd take a sec to update everyone on what we're working on.

In the very short term, we'll release Starry Night 7.0.2, mostly to address crashes and other incompatibilities that weren't discovered during beta-testing. We're focusing on issues that make it difficult to use the app, and features that might be broken. I'm taking this week to true up the Equipment list too.

In the weeks to come, we're going to take a solid look at all of the feature requests, suggestions and comments all of you have made, as well as usability issues discovered by our Beta-Testers.

We'll be rewriting the Observation Logging feature, with a particular emphasis on sharing logs... with each other and with other applications. We'll be sure to enable importing of your V6 logs, not to worry!

In addition to improving all of the obvious observing features, we'll be looking at other ways to share experiences with your friends and co-observers, improve add-to and refine our databases, and improve the speed of the application.

Stick with us. Lots of interesting things to come.

Importing SN6 data to SN7 (Or: How I learned to stop worrying and love Sky Data overrides.)

Because of the ubiquity of the internet, the vast volumes of data available to us (and therefore you, the SN user) and new security requirements imposed by operating systems, Starry Night 7 has introduced the idea of a "dynamic" (writeable) Sky Data folder.

In previous versions of SN, the application itself would edit (write to) files in its own Sky Data folder located either in the application package (on OSX) or in the Program Files folder (Windows) and this is now considered very bad behavior.

For that reason, any time SN needs to write/modify a file, we so in a new Sky Data folder located at:

(Windows) \Users\<YourUserName>\AppData\Local\Simulation Curriculum\Starry Night Prefs\

(Note that the AppData folder is often "hidden". A quick Googling can show you how to un-hide it)

(OS X)  /Users/<YourUserName>/Library/Application Support/Simulation Curriculum/Starry Night Prefs/

Note that this is where any "streamed" data will be located too.

While we've made every effort to hide this ugliness from you the user, if for any reason you want to get your hands dirty and edit a file manually, it should first be copied to the same respective path (e.g. /Sky Data/Planet Images) in this new folder, then edited there.

Any file located in this new Sky Data folder should have the effect of overridding the one in our static Sky Data folder.

Now, for the part you've all been waiting for. How do you get all of your Equipment, Distance Spheres, Locations, Preferences, Custom (User) Planets etc. from SN6 to SN7? 

Simply copy the individual files from your old "Prefs" folders into the matching locations in the new "Starry Night Prefs" folder!

Have fun!

Starry Night 7: Motivation, Process, Future

As many of you have noticed, we're back with a brand new version of Starry Night! Rather than list all of the cool new features, I thought I'd take a moment to make clear our motivations for the changes in SN, our process getting to where we are now, and plans for the future.

For many of our loyal, longstanding users, the new user interface is a big change from what they're used to. Our motivation for the change was simple: the interface had gotten to the point where users were spending more time looking at (or looking for!) controls, than looking at the sky. We needed something new, cleaner, less obtrusive.

In our redesign, we followed the general philosophy that the UI should "be there when you need it, disappear when you don't."  The focus should always be on the sky view, never the controls. This for example, is why we moved the Find pane from the left to the right... in general, people read left-to-right. Left is more prominent, so the sky view should always be at the left.

Our move to a "Universal Search" function was similarly motivated. 

We found that over the years, so many of the great new features that we had added were buried under layers of user interface, that not only were they hard to use, but people often never found them in the first place.

With the ability to do a textual search for control items (not just named objects in the night sky), we have opened up a host of existing features to users who didn't even know about them! No longer do you need to know exactly what setting you're looking for, open the Options panel, visually search for it, and click to make a change... simply search for the word (or even a related word) that you're looking for, and you'll probably find it.

While I think we have succeeded in many, many ways, we still have much work to do.

Going forward, we plan on continuing with the idea of "less is more." Not in terms of what you can do (indeed, we are addingfeatures and data) but in what ways you are distracted from what you are doing. Think: more of what you want, less of what you don't.

While we have released it into the wild, we're far from done with it. Starry Night 7 should be thought of as a journey, not a destination.

Photos of Apollo missions

Houston's Lunar and Planetary Institute has made available almost 20,000 otherworldly images taken during Apollo missions (http://www.lpi.usra.edu/resources/apollo/catalog/70mm/ ). Dig deep and you'll find plenty of Instagrammable moments (eg. http://www.lpi.usra.edu/resources/apollo/frame/?AS16-116-18636 )

Can you match the photos with Apollo mission paths in Starry Night?

Orion and His Friends and Enemies

On winter evenings, the sky is filled with bright stars, more than at any other time of the year.

On winter evenings, Orion dominates the sky, surrounded by numerous striking constellations, all decorated with brilliant stars.  Credit: Starry Night Software

Central in the southern sky is the constellation of Orion the Hunter. Along with the Big Dipper, this is probably the most easily recognized constellation, and the starting place for a stargazing adventure.

We apologize to our readers in the southern hemisphere, where it is summer. But even in the south, Orion dominates the sky right now. Turn the chart upside down, and everything we say will still apply.

Orion itself sits astride the celestial equator, half way between north and south celestial poles. This makes Orion an “equal opportunity” constellation, well seen everywhere on Earth except at the poles.

The main figure of Orion is a large rectangle of four bright stars, including two of the brightest stars in the sky, Betelgeuse at upper left and Rigel at bottom right. These four stars represent the shoulders and knees of a might hunter.

The thing that most people notice first is the diagonal line of bright stars right in the middle of the rectangle, which represent the giant’s belt, worn at a jaunty angle. Hanging from his belt are three stars representing his sword.

If you’re located at a dark sky site, you will be able to see more details in Orion. His rather small pointy head is represented by a triangle of stars. His right arm raises a club and his left arm raises something towards Taurus the Bull. Some legends have this as a lion’s skin, others as a shield.

I like to see Orion as a superhero beset by evildoers on all sides, but also with friends and allies.

Taurus, to his upper right, is marked by a bright red star, Aldebaran, in the midst of the cluster of stars known as the Hyades. A bit higher is a second cluster, the Pleiades. Both clusters are easily seen with the naked eye. Orion is shielding himself from the Bull with his lion’s skin.

Below Taurus, to the right of Orion, is a meandering stream of stars which early astronomers saw as the river Eridanus. This river meanders below the southern horizon for most people in the U.S.A., but those in southern Florida and Texas may catch a glimpse of its destination, the first magnitude star Achernar.

Above the horns of Taurus is Auriga the Charioteer, marked by Capella, the sixth brightest star in the night sky. I see him as the cavalry riding to Orion’s rescue.

Above and to the left of Orion is the constellation Gemini, the Twins, with its two bright stars Castor and Pollux. Currently this is where the planet Jupiter is located, outshining all the stars. So which is Castor and which is Pollux? I remember them because Castor is closest to Capella, both starting with a “C,” while Pollux is closest to Procyon, both starting with a “P.”

Orion, like all good hunters, is accompanied by his two hunting dogs, big and small: Canis Major and Canis Minor. “Canis” means “dog,” “major” means large, and “minor” means “small.”

Each dog contains one bright star: Procyon in Canis Minor and Sirius in Canis Major. There is only one brightish star besides Procyon in Canis Minor, making it more like a hot dog than a real dog. Canis Major is more like a real dog, sitting up with a head, body, and two hind feet. Sirius and Procyon are the first and eighth brightest stars in the night sky, and among the nearest to the sun at 8.6 and 11.4 light years distance respectively.

Between the two dogs is a faint constellation with a long name: Monoceros. “Mono” means “one” and “ceros” means “horn,” so Monoceros is a unicorn. Although it lacks any bright stars, it is one of the richest constellations in deep sky objects, because an arm of the Milky Way lies in this direction.

What is beneath Orion’s feet? Usually called Lepus the Hare, I like to think of this as Monty Python’s Killer Rabbit, yet another foe for our hero to vanquish.

Everything I’ve described can be seen with the unaided eye, even in fairly light polluted skies. If you have binoculars or a small telescope, there are incredible riches to be discovered, such as the clouds of glowing gas in Orion and Monoceros, the star clusters of Taurus, Auriga, Monoceros, and Canis Major, and the galaxies of Eridanus.

Venus Shines at its Brightest

This week Venus will be shining at its brightest, low in the southwestern sky just after sunset. Venus’ brightness is the result of geometry.

At 2 p.m. EST on Friday December 6, Venus will be shining at its brightest. Look for it in the southwestern sky just after sunset.  Credit: Starry Night Software

As Venus moves around the Sun, closer to it than the Earth, we see it illuminated from all angles.  This causes it to pass through a series of “phases” similar to the moon. When it is on the far side of the Sun, called “superior conjunction,” it is fully illuminated from our point of view, and we see it as a “full Venus.” It is 100 percent illuminated but far away, only 10 arc seconds in diameter.

When Venus is at “greatest elongation,” farthest from the Sun in our sky, as it was on November 1, we see it as a “half Venus.” When it passes between Earth and the sun, as it will on January 11 2014, called “inferior conjunction,” it is illuminated from behind, just like the new moon.

The brightness we see from Venus depends on two things: its phase and its distance from us.  It should be brightest at its “full” phase, like the Moon, but at that time it is at its furthest from us. At “half” phase, as it was on November 1, only half of it is illuminated, but it is much brighter because it is much closer.

As Venus nears inferior conjunction, its illuminated portion shrinks down to a narrow sliver. This causes it to fade in brightness. But it is also getting closer to us, which makes it brighten.  This week, these two factors balance out, and we will see Venus at its very brightest. It is neither “half Venus” (50 percent illuminated, 25 arc seconds in diameter) or “new Venus” (0 percent illuminated, 60 arc seconds in diameter), but somewhere in between. In fact it is 26 percent illuminated and 41 arc seconds in diameter. This is the “Goldilocks point” when distance and  phase combine to produce the greatest brightness.

This week Venus will shine with a brightness of –4.9 magnitude, on the upside-down brightness scale that astronomers use. It is based on the brightest stars being magnitude 1 and the faintest stars visible being magnitude 6. Thus the brighter the object, the smaller its magnitude number. 

Astronomers extended this scale into the negative for really bright objects.  The brightest star in the night sky, Sirius, is magnitude –1.4. The full moon is –12.7 and the sun is –26.8. So Venus this week will be considerably brighter than Sirius, but nowhere near as bright as the moon. It is bright enough to cast shadows, when observed on a moonless night from a dark location.

Even though Venus is the brightest object in the night sky other than the moon, surprisingly few people have seen it in its current apparition. That’s because at this time of year the ecliptic, the path of the planets across the sky, makes a very shallow angle with the horizon in the northern hemisphere. Although Venus is very bright, it is also very low in the sky, so is often blocked by clouds or buildings.

This week, find yourself a location with a low southwestern horizon and look for Venus. Watch it as it slowly sets, and see if you can see it change color from white to orange to red as it nears the horizon, just as the sun and moon do.

Did you know that you can see Venus in daylight? The best time to look for it will be on Thursday this week. Look for the narrow crescent moon in the afternoon sky above and to the left of the sun. Use that to locate Venus, just below the moon. You may need binoculars to first spot it, but once you know where it is relative to the moon, it’s very easy to see.

Comet ISON at Perihelion

Astronomers all over the world are training their eyes and telescopes on Comet ISON as it approaches its closest distance to the sun, called perihelion.

At noon on Wednesday November 27, Comet ISON should be visible at the plotted location in the view of the SOHO satellite’s LASCO C3 camera. The next day it will pass perihelion at 1:44 p.m. EST. If it survives, it will be moving towards the top of the LASCO field. Credit: Starry Night Software

Perihelion will occur at 1:44 p.m. on Thursday November 28, Thanksgiving Day in the U.S.A.

Rather than the traditional football game, we’d suggest you watch ISON’s progress around the sun instead.

While some predictions suggest that the comet may be visible in daylight, we’d rather you didn’t risk your vision by staring at the sun. It might be possible to block the sun from view with a well placed chimney or lamp post, but there is a better way, and it’s 100 percent safe.

There are several satellites in orbit around the sun which are trained on the sun all the time. One the oldest and still one of the best is SOHO, the Solar and Heliospheric Observatory.

SOHO was launched in 1995, and carries an array of cameras pointed at the sun. For our purposes, the most interesting one is the Large Angle and Spectrometric Coronagraph #3, or LASCO C3 for short. This shows a field of view about 32 degrees wide. The sun itself is blocked by a disk at the end of a stalk, its diameter marked by a small white circle. Because SOHO is in space, there is no atmosphere to scatter the sun’s light, so we can see the stars surrounding the sun, just as if we were watching a total solar eclipse. Actually, the view is much better than at a total eclipse, with stars down to about 7th magnitude visible.

Very early in SOHO’s history, astronomers realized that they could observe comets passing very close to the sun, called “sungrazers.” To date, more than 2400 comets have been discovered by careful skywatchers scanning SOHO’s LASCO C3 images. The images from LASCO are refreshed regularly about an hour apart, and relayed immediately to this web page:

http://sohowww.nascom.nasa.gov/data/realtime/c3/512/

Whenever you check this page, you will see the most recent image from space, usually not more than an hour or two old. Go there right now, and you will see the sun’s current coronal activity and, in the background, the stars on the far side of the sun. Over the next few days, if all goes well, you will see Comet ISON’s progress around the sun. It should enter LASCO C3’s field of view at the right side on Tuesday November 26.

ISON will pass just below the sun on Thursday and then move upwards, leaving the field on Saturday afternoon. In our graphic, the yellow circle shows the LASCO C3 field of view, the gray parabola is ISON’s path, and the stars of Scorpius are in the background. ISON is shown in its position on Wednesday November 27.

It’s impossible to say in advance exactly what we will see in the next few days. By watching the comet’s progress in the LASCO camera, you will participate in a great astronomical adventure.

Will the comet break up? Will it continue on to be one of the brightest comets in history? As of this writing, no one knows, but by watching it on LASCO, you will know as soon as anyone.

The Galaxies of Autumn

As the Earth moves in its orbit around the sun, new constellations are revealed in the east as the old ones disappear into twilight. The bright stars of the Summer Triangle will soon be replaced by the even brighter stars of Orion and his winter companions.

Use this chart to locate the galaxies of autumn. Credit: Starry Night Software

During this period of transition, we find ourselves looking outwards from our own galaxy into intergalactic space. This is one of the two best times of the year to hunt for galaxies.

The stars of autumn are relatively faint, as we are looking out away from the disk of our galaxy. To see these fainter stars you may need to travel away from your urban or suburban home to seek out the darker skies of the countryside.

After twilight falls, look eastward to see the Square of Pegasus, formed by four second magnitude stars, about the same brightness as the stars of the Big Dipper. As the Square is rising in the east, it will appear more as a diamond than a square. The leftmost star of the diamond, Alpheratz, marks the head of Andromeda. Two streams of stars extend to the left from Alpheratz, pointing towards Perseus, just below the "W" shape of Cassiopeia.

These constellations provide the framework of relatively nearby stars in our own galaxy, the Milky Way, through which we look locate our neighboring galaxies beyond.

Most people have never seen another galaxy. In fact, most people today have never seen the galaxy in which we live, because the widespread glow of light pollution blocks the Milky Way's faint light. It’s only on rare occasions of major power failures that city dwellers get to see the Milky Way.

To locate our nearest galaxies, look for the middle star in the lower chain of Andromeda, Mirach. Just above it is a fainter star in the upper chain. Draw an imaginary line from Mirach to this second star, and extend it the same distance. This will take you to the Andromeda Galaxy.

What will you see? With the unaided eye, probably nothing, unless you are at a very dark location. However, with ordinary 7x50 or 10x50 binoculars, you will see a tiny faint glowing cloud. Oddly enough, if you point a telescope at this cloud, you will probably see less than with binoculars. This is a case of less being more: the wide field of view of the binoculars sets off the view of the Galaxy perfectly.

This faint glowing cloud may not seem impressive, until you realize that its light has been traveling for more than two million years to reach your eyes. When that light began its journey, our ancestors were just a bunch of small primates wandering on the plains of Africa.

Go back to Mirach and its companion, but this time, follow the line in the opposite direction. This will lead you to an even fainter cloud, the Triangulum or Pinwheel Galaxy. This is a smaller galaxy than Andromeda, but located at about the same distance from us. Even though this is one of the brightest and nearest galaxies in our sky, it is unusually difficult to see. That’s because it is almost at right angles to our line of vision, so we are seeing it in plan view. As a result its feathery edges blend into the background, and we have no sharp edge to catch our eye.

Usually you need binoculars to see the Triangulum Galaxy, but sharp eyed observers at very dark locations have managed to see it with the naked eye, making it the farthest object that the human eye can see unaided.

Partial Eclipse of the Moon

There will be a partial eclipse of the moon on Friday October 18. The moon will pass through the edge of the Earth’s shadow, ending up partially in the shadow of the Earth.

The moon passes through the edge of the Earth’s shadow at dusk on Friday October 18, as seen from eastern North America.  Credit: Starry Night Software

If you look closely at any shadow cast by the sun, say the one cast by your hand on a piece of paper, you will notice that the edge of the shadow isn’t sharp. That’s because the sun is not a point source of light. It is a disk, so the shadows it casts are slightly fuzzy. The solid dark part of the shadow is called the “umbra,” Latin for “shade.” The fuzziness is called the “penumbra,” Latin for “almost shade.”

When a shadow is cast by a nearby object, the penumbra is very slight. When the shadow is as far away as the moon is from the Earth, the penumbra is quite wide.

The graphic shows the situation at maximum eclipse at 7:50 p.m. EDT on Friday night, October 18. The inner circle is the umbra, the outer circle the penumbra. The moon makes it part way into the penumbra, but misses the umbra completely, hence this is a “partial penumbral eclipse.”

For observers in Africa, Europe, and western Asia, the eclipse will occur in the middle of the night when the moon is high overhead. The partial shading will be visible as a slight reddish dimming of the normally bright full moon.

For observers in North America and South America, maximum eclipse will be around the time of moonrise, which is also the time of sunset. This will make the eclipse difficult to see, because we will be looking for a slight dimming of a moon which is already dimmed by passing through a great deal of the Earth’s atmosphere.

The farther east and north you are located, the better your chances of seeing this eclipse. For example, in New York City, the moon will rise at 5:59 p.m. EDT, and will be at an altitude of 20 degrees at maximum eclipse. In Chicago, moonrise is at 5:54 p.m. CDT and the moon’s altitude only 9 degrees at maximum eclipse. In Los Angeles, moonrise is at 6:09 p.m. PDT, more than an hour after maximum eclipse, so the chances of seeing the eclipse are zero.

For observers in North America, the effects of the moon’s shadow will be most pronounced on the lower right corner of the moon. The shadow will probably be more pronounced in photographs than with the naked eye, so this is a good opportunity to get out your telephoto lens and photograph the rising moon. Remember that maximum eclipse will be at 7:50 p.m. EDT and 6:50 p.m. CDT.

Triple Eclipses on Jupiter

A rare planetary viewing event occurs this week when three of Jupiter’s largest moons cast their shadows simultaneously on the planet below them: three solar eclipses at the same time.

Three of Jupiter’s moons cast their shadows simultaneously on the planet beneath them on Friday night and Saturday morning, October 11 and 12. Picture the sun coming over your left shoulder, causing the three moons on the left to cast their shadows on the planet to the right, causing eclipses of the sun in three different locations on Jupiter. Credit: Starry Night Software

An eclipse of the sun happens when a moon casts its shadow on the planet below it. For observers located where the shadow falls, the sun appears to be completely blocked by the moon, and they are able to see the prominences and corona around the occluding moon.

In the Earth-moon system, the Earth is a fairly small target and its moon is far away, so it’s rare for the moon’s shadow to fall on the Earth. On average it happens about twice a year, and the diameter of the shadow on the Earth’s surface is quite small, only a couple of hundred miles in diameter. To see a solar eclipse, you need to be in exactly the right place, the place where the moon’s shadow falls.

Because our moon’s orbit is tilted with respect to the Earth, most of the time the moon’s shadow passes above or below the Earth, and no eclipse occurs. Only about twice a year do the three bodies line up exactly so that the moon’s shadow touches Earth. This next happens on November 3.

With Jupiter, the situation is different. Jupiter has four large moons: Io, Europa, Ganymede, and Callisto. These are relatively close to Jupiter and Jupiter is much larger than Earth. As a result, the shadows of Jupiter’s moons cross its face very frequently. The innermost moon Io causes an eclipse on Jupiter once every 1.8 days (42 hours). Even the outermost moon, Callisto, traveling much more slowly, should cause an eclipse every 17 days. In fact it does so less frequently because, like our moon, sometimes its shadow passes above or below Jupiter.

So, if eclipses on Jupiter happen very often, why don’t we see more of them? The timing has to be exactly right. Io may cause an eclipse on Jupiter every 42 hours, but the eclipse itself lasts only a little over 2 hours. Also, Io’s shadow is very small; you need a telescope with at least 90mm aperture to see it. If you aren’t looking for it, you probably wouldn’t see it at all, it’s that small. Also, because of the Earth’s rotation, Jupiter is below the horizon half the time, and often lost in the daylight sky.

If the shadows of its moons fall so often on Jupiter, what are the chances of two shadows falling simultaneously? Pretty good, it turns out. This is especially true because there is a resonance between the orbits of Jupiter’s satellites. Europa’s period of revolution is almost exactly twice that of Io, and Ganymede’s almost exactly four times. Only Callisto doesn’t keep step with the inner satellites.

As a result, double shadow transits usually happen in a group. The current group started with a double transit of Io and Europa’s shadows on September 28 and will continue every few days until November 13.

The rarest of all shadow transit events is when three shadows cross Jupiter’s face simultaneously, and this will happen this coming Friday night, October 11, stretching on into Saturday morning, October 12. Because of Jupiter’s present location, this event is mainly visible in the eastern part of North America. The event is in progress when Jupiter rises around midnight on the east coast, but is completely over by the time Jupiter rises on the west coast. Here are the times of the events to look for in Eastern Daylight Time—some events occur before Jupiter rises:

11:12 p.m. Callisto’s shadow enters

11:24 p.m. Europa’s shadow enters

12:32 a.m. Io’s shadow enters: all three shadows visible

1:37 a.m. Callisto’s shadow leaves

2:01 a.m. Europa’s shadow leaves

2:44 a.m. Io’s shadow leaves

Keep an eye on the moons themselves, because they will also begin to cross Jupiter’s disk: Io at 1:48 a.m. and Europa at 2:02 a.m. There’s an added bonus in the Great Red Spot also transiting at this time. It helps to visualize the moons’ movements in three dimensions, with the sun seeming to come from over your left shoulder. Sometimes you get an almost three-dimensional effect with the moons casting their shadows on the planet beneath.

If you miss this event, there will be three double shadow transits later this month visible over most of North America, on October 16/17, 18/19, and 25/26. In each case, the events mostly occur after Jupiter rises around midnight on the first date, so that’s the night you should mark on your calendar. Remember that the date changes at midnight.

Starhopping to Uranus

Most of the planets in the solar system hover close to the sun, which illuminates them and makes them among the brightest objects in the sky. The outer planets, Uranus and Neptune, are far from the sun and catch few of its rays, making them dim and hard to find.

The planet Uranus is currently located in the dim constellation of Pisces. Although just visible with the unaided eye, Uranus is brighter than any of the stars in this area, so is relatively easy to locate with binoculars. Credit: Starry Night Software

Uranus, for example, reaches opposition with the sun on Thursday October 3. Directly opposite the sun in our sky, it is at its closest and brightest, yet it is only just barely visible to the unaided eye in a dark moonless sky. For most people, a binocular will be an essential tool for spotting Uranus.

This is done through a technique popular with amateur astronomers called “starhopping.” We use the brighter stars as guideposts to locating faint or distant objects. In this case, we start with the most prominent group of stars in the autumn sky: the four stars that form the Square of Pegasus. Although not among the brightest stars, these are all good second magnitude stars, about as bright as the stars in the Big Dipper.

Many people who go looking for the Square of Pegasus miss it because it is so large. The four sides of the Square are roughly 15 degrees long, about the length of the handle of the Big Dipper. Look for them in the east as the sky gets dark around 9 p.m. At that time the Square is rising, so is tilted over, making it more of a diamond shape than a square.

Now we begin our “starhop.” We start with the two stars that form the bottom of the square (if you’re in the northern hemisphere). Make that one side of a south-pointing equilateral triangle. The southern point of the triangle marks the “Circlet,” part of the dim constellation of Pisces. This is an oval of dim stars, more easily seen in binoculars than with the unaided eye.

To the left of the Circlet is a chain of stars, part of the chain that binds the two fish of Pisces together. The first two stars in this chain are a bit brighter than the rest. About half way between these two stars, and a bit to the south, you should find Uranus.

How will you know you have found it? First of all, although dim, Uranus is brighter than any of the stars in this area. Secondly, it has a distinctive blue-green color, quite unlike any star. Finally, if you plot its position relative to the stars, and check again in a few days, you will find that it has moved to the right.

Of course, the acid test is to point a telescope at it. Most newcomers to astronomy are surprised at how small any of the planets appear in a telescope, but Uranus is smaller still, a mere 3.7 arc seconds in diameter, about a tenth the size of Jupiter. Unless you have a very large telescope, it will appear as nothing more than a tiny blue-green pinhead.

Comet ISON's flyby of Mars

Today, comet ISON will fly by Mars at a distance of 0.07 AU.  The satellites in orbit around Mars and the rovers on the ground are at the ready to snap their pictures.  Thankfully, Curiosity has been designated "essential personnel" and will be operational despite the US government shutdown.

View of ISON from Mars (rendered by Starry Night)

Autumn Monsters

As the constellations of summer depart from our sky, they are replaced by what are often called "the watery constellations." These include normal sea creatures like fishes and dolphins, and even Aquarius carrying a water jug.

The constellations of autumn include some strange monsters like Capricornus, the Sea Goat, Cetus, the Sea Monster, and Pegasus, the Flying Horse. Credit: Starry Night Software

Among these watery creatures are some strange creatures which we would call monsters: strange combinations of parts of unrelated animals.

The first to appear is Capricornus, the Sea Goat. Seen in the lower right of our chart looking southward on an autumn evening in the northern hemisphere, he combines the front end of a goat with the rear end of a fish. Most people would be hard pressed to see either a goat or a fish in this large triangular group of stars. I see it more as a tricorn hat turned upside down. The front end of the goat, to the right, is marked by two wide double stars, Algedi and Dabih, a fine sight in binoculars. “Algedi” or “Al Giedi” is Arabic for “the goat.” The rear end of the fish is marked by Deneb Algiedi, which translates from Arabic as "the tail of the goat."

Much of our knowledge of ancient astronomy, along with mathematics and other sciences, has been passed down to us by medieval Arab scholars. In the process many of the old star names were translated into Arabic. As a result, astronomers learn a bit of Arabic. "Deneb" is Arabic for tail, so turns up in many star names in constellations derived from animals. The most famous is Deneb in Cygnus, marking the tail of the Swan.

"Al" is Arabic for "the" and turns up in many scientific words like "algebra," "alcohol," and "alkali."

In the lower left corner of our chart we find another monster, Cetus. Modern astronomy books usually translate this as "the whale," but our chart shows a much stranger creature. it has the head of a dragon, webbed feet, and a fishy tail. This tail is marked by one of the few bright stars in this part of the sky, Deneb Kaitos. With our new knowledge of Arabic, we can translate this easily as "the tail of the whale."

Buried in the heart of Cetus is a remarkable star called Mira, which means “wonderful” in Latin. This was discovered by David Fabricius in 1596 to be a star which varies in brightness, one of the first variable stars to be discovered.

Flying high above these watery creatures is yet another monster, a horse with wings called Pegasus. This is probably one of the most familiar mythological creatures, so familiar that most people never think of how strange a flying horse would be. The celestial flying horse is marked by four fairly bright stars forming an almost perfect square, the Square of Pegasus.

When I first went looking for Pegasus in the sky, I made a common beginner's error. Because I was using a small star chart, I looked for a small square of stars in the sky, and totally missed it. The constellations in the sky are much larger than they appear on star charts. So look for a really large square of stars.

Actually, only three of the four stars in the Square are part of Pegasus. The star in the upper left corner is Alpheratz, actually part of the constellation of Andromeda. But that is another story.