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    My Journey through the Astronomical Year

    Think of this as a "companion text" to this, the main web site. Not required reading, butI hope you'll find it interesting and helpful.

Events July 2011 – Neptune celebrates Year One! Plus – let the Moon find stuff for you.

Can you imagine it? Neptune, the most distant full-sized planet, becomes One Neptunian Year Old on July 12! Should we sing happy birthday? Or Happy New Year?  Or how about just getting to know it a little better, then seeing if we can locate it with our binoculars?

Click for larger image. (Graphics courtesy of NASA - Neptune "facts" added by me. )

That’s right – Neptune was discovered on the night of  September 23/24, 1846.  That’s when it entered the awareness zone of the inhabitants of the third rock from the Sun.  And it has taken it all this time to make a single trip around Sol – almost 165 years.

So – your challenge this month will be to reprise the discovery of Neptune – but we won’t ask you to do the astounding math that led to its discovery in the first place.  What I really like, is when Neptune first was discovered, a graduate student working on the project exclaimed: “That star is not on the map!”

You bet – because that “star” is not a star, but a planet – a “wanderer.”  But when you look at it with your binoculars it will look pretty much like any other star – which is why it fooled some of the greatest observers, including Galileo.  In fact, even if you own a small telescope it will take very high power and steady seeing to see the disc of Neptune. Galileo recorded this “star” twice in 1613 even noting that it had moved – but he didn’t understand the significance of what he had seen. Of course, he had a lot of other things on his mind at the time and everyone assumed then that the Solar System ended with Saturn.  Who even dreamed there were two huge, exotic chunks of ice out there, Uranus and Neptune, yet to be discovered?

But first . . . we interrupt this program for this special message . . . !

I have to admit, Neptune is a challenge object, and if you’re just starting out with your exploration of the universe, why not let the Moon be your guide this month to some more modest finds? It can lead you to Mercury, Mars, one of our bright guide stars, Antares – and if you’re an early riser, even to the Pleiades! So if you feel finding Neptune is a bit much for you, then try using the Moon as a “guide star” to help you discover brighter objects you can see with the naked eye.  Jump to here for all the details.

 . . . and now back to our regularly scheduled program

OK – Neptune shines on the bright side of magnitude 8, which means it should be visible in ordinary binoculars under reasonably dark skies, although 50mm binoculars will give you a better chance, and my favorite  for this kind of a  project are a pair of inexpensive 15X70 Celestrons. I found it in a few minutes with 15X70 binoculars – with 7X35 binoculars it was just on the edge of visibility. If your skies are real dark, they would work, but I recommend at least 50mm binoculars for this project.  But whatever your binoculars, it’s important you know two things about them – their field of view, and how bright a magnitude 8 “star” such as Neptune will appear in them.

Field of view (fov) is fairly easy since on most binoculars it is written on them in degrees. If it isn’t you can make the assumption that if they are 7 power, then they probably have a fov of about 7 degrees. Ten power binoculars will have a smaller field, closer to 5 or 6 degrees, and the 15X ones I favor have a 4.5° fov.  I show a couple of different fields on the accompanying star charts so you can get an idea of how much sky you see when you use your binoculars.

Knowing how bright a magnitude 8 star should appear in your binoculars is a little tricky, but fortunately there is one fairly close to Neptune, and it will be a big help. Your binoculars, of course, gather much more light than your eye and thus you will see many more stars than you can see with your eyes alone.  Not only that, but stars you do see with the naked eye will appear brighter in the binoculars.

Start the search!

Yes, let’s get going. The Moon will offer the least interference in the first 13 days of the month.  If you don’t find Neptune by July 13, you may want to wait until the Moon is past last quarter – the final week of July.  This is an early morning project, since Neptune doesn’t rise until about three hours after sunset and  you really want it to be as high in the sky as it gets to make the search easiest.  Unfortunately, by the time Neptune is due south and at its highest point, morning twilight has already begun. So I suggest you fudge it and set your observational goal for a  2 – 3 am start time.

At that hour you want to look generally south – well, a tad east – into a sky that is really quite empty of bright  stars and clear guideposts.  The brightest star in the general vicinity is Fomalhaut, but there are two other reasonably bright stars nearby that can serve to  guide you. Take a careful look at this chart. What looks like a triangle drawn by a 2-year-old on the right is actually the relatively faint constellation Capricornus. In classic terms you can put these stars together to form a mythical creature known as the “Sea Goat” – half goat, half shark. Good luck. I see a big awkward triangle and the tail end – eastern most – has two third magnitude stars that are pretty easy to pick up, the brighter being named Deneb Algiedi.

Use this chart to make sure you have the general location of Neptune. Click for a larger version. Read more about it below. (Prepared from Starry Nights Pro screen shot. )

For a  orinter friendly version of this chart, click here.

A tale of two tails

Get your general bearings by identifying the  three brighter stars in view. Fomalhaut is a first magnitude guidepost star and will be about 16 degrees above the horizon while Neptune is more than twice that altitude. Deneb Kaitos (the Sea Monster’s tail) is magnitude 2 – the same brightness as the North Star, Polaris.  Deneb Algiedi (the Sea Goat’s tail) is a bit dimmer at magnitude 2.8, but more important to our search. Finally, the “Circlet” is in Pisces – yep we have a whale, or sea monster, some fish, and a “sea goat,” a very nautical section of sky. The “Circlet” consists of fourth and fifth magnitude stars in Pisces and if you can see these, count yourself as having good, dark skies.  But don’t expect the “Circlet”to jump out at you – these stars are as faint as most of the stars in the Little Dipper.

And now, Neptune!

A simple star hop takes you to Neptune - see explanation in text below. Click for larger image. (Prepared from Starry Nights Pro screen shot.)

For a printer-friendly version of the above chart, click here.

Using this chart – First, your binoculars may show more stars than these, but they will all be fainter than Neptune. The larger numbers, 1, 12, and 31, mark the position of Neptune on those dates in July 2011. Of course, you may spot it on a different date and thus at a slightly different position along an imaginary line connecting all the dates. The other numbers you see represent star magnitudes to one-tenth of a magnitude – only we don’t put a period in the number because it might be mistaken for a star. Thus “78,” for example, means magnitude 7.8.

Hop 1 –  Locate Deneb Algiedi and its slightly dimmer companion in your binoculars.

Hop 2 – Use this bright pair as a rough guide as you move to the left (eastward) with your binoculars and come to Magnitude 4.3 Iota Aquarii.  (You should be able to see this with your naked eye, as well.)

Hop 3 – Draw mental line between Iota and slightly brighter Theta Aquarii. It’s about 6.5 degrees away so you may not fit it in the same binocular field.  But Neptune lies right along that line.

Hop 4 – The 5.4 magnitude star about one third of the way along this line between Iota and Theta,  anchors a rectangle (as shown)  that includes stars of 7.4, 6.6, and 7.8 magnitude. That last star  – magnitude 7.8 – is especially interesting because that’s the exact magnitude of Neptune.  So on the first of July, for example, that star is on one side of the 5.4 star while Neptune is about the same distance away on the other side. It’s that 7.8 magnitude star that tells you how bright such a star should appear in your binoculars – very faint – and thus tells you what you should expect to see in terms of Neptune.

Of course, if you really want to be sure you have found the “wanderer” Neptune, then you need to make your own chart – you can do that from the one supplied – and mark on it where you believe Neptune is on at least two nights. Ideally they would be several days apart so you could detect the motion.

Planet hunting – at least hunting a faint, distant planet like Neptune –  is not easy.  Just taking up this little challenge should help you appreciate the task astronomers had 165 years ago.  But if you want to know more, I highly recommend you read the article in Sky and Telescope magazine for  July 2011. You can find the story told elsewhere on the Web – it involved  mathematical predictions from two different sources – but what i feel is the definitive article on the subject is in  this month’s S&T.

Let the Moon be your guide

Here’s a simple idea. Everyone can find the Moon when it’s in the sky, so why not take advantage of its travels and use it to point the way to bright stars and planets?

OK? Let’s do that! As the Moon changes location and size during the month, I’ll point out some key items in its neighborhood.  You, of course, have to look on the date specified,  And here are a couple of quibbles:

1. As the Moon gets closer to being full it’s glare will tend to drown out all but the brightest stars near it. Sometimes you may even need binoculars to see some stars that are near.

2. My charts are precise only for my latitude and longitude – roughly 42° N latitude and 71° west longitude – the East Coast of America. If you are on the West Coast the Moon will have moved a bit eastward, for example,  (It moves at the rate of half a degree an hour – that means it changes position by the size of its own diameter every hour.  This should not matter much. Just use the charts as a general guide if you live in  North Amerca.  Elsewhere in the world the difference could be significant – as much as about 12 degrees,

That said – here are the key dates to look for the Moon – and the objects expected near it, for July 2011.  Pick a date and give it a try. Even if you know the object, it could help you develop a better feel for the night sky.

July 2 and 3  – Locate  Mercury

Always hard to find because it is frequently lost in twilight when visible, Mercury makes a good appearance this month in the western evening sky. Start looking about 30 minutes after sunset.  You may also pick up Castor and Pollux, but they will be fainter than Mercury. And finding any of these objects requires an unobstructed western horizon and clear skies. Binoculars are extremely helpful as well.

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

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

July 4 – passing Regulus

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

July 7 – first quarter Moon with Saturn, Spica, and the “Sail”

I love this grouping. It will help you find Saturn, always a delight in any size telescope, as well as identify another bright “guidepost” star, Spica. Finally, though you’ll probably need binoculars to pull it out of the Moon’s glare, the “Sail” is a favorite asterism, for it looks like the sail on the old, gaff-rigged Beetle Catboat I spent so many wonderful summer days sailing.  These stars are more formerly  a major part of the constellation Corvus.

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

July 11 – to the Heart of the Scorpion!

Here’s a constellation I love with a bright, red guidepost star, Antares.  And here’s the moon – getting near full and passing very close to Antares which is at the heart of Scorpius. Try using binoculars if you don’t see this bright star at first – you should be able to pick it up with it’s two companion.  But the Moon will certainly do its best to drown it out.

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

Time to switch to the morning sky! July 24 – the Moon and Jupiter.

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

July 25 – the Moon and the Pleiades

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

July 26, 2011 – Crescent Moon, the Hyades, and Aldebaran

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

July 27, 2011 – Could that be Mars? you bet!

The small, red planet is barely first magnitude. But since it is within about three degrees of the Moon you should be able to fit them both in the same binocular field of view about two hours before sunrise when they are roughly 10 degrees – one fist – above  the eastern horizon.

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


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