Winter from your back yard: Jupiter and the Orion vicinity

Winter from your back yard: Jupiter and the Orion vicinity

Postby debbie-moran » Thu Feb 05, 2015 9:44 pm

Houston is pretty light polluted, but there is still a lot to see from your back yard. Jupiter reaches opposition the night of our next meeting on February 6th. "Opposition" is just as it sounds...on that night Jupiter is "opposite" us from the sun in its orbit. That means that it is highest around midnight and most importantly that it is about as close to us as it can get in its orbit, therefore the image is as large as it is going to be until the next opposition. It also means that Jupiter rises near nightfall. In the coming months, it will rise increasingly early and be increasingly better placed in the early evening although it will also be gradually shrinking in size in the telescope. Now is the time to observe Jupiter. Jupiter will be discussed in depth at the February novice meeting.

A good place to start learning winter constellations is with Orion whose three belt stars all in a row are unmistakable. These are Alnitak, Alnilam and Mintaka: http://www.daviddarling.info/encycloped ... sBelt.html. To find Orion high in the south at 8:00 pm in early February, use this free map at http://www.skymaps.com/skymaps/tesmn1502.pdf. (Monthly maps can be downloaded every month at http://www.skymaps.com. Be sure to find the Northern Edition maps, the first of the listings.) Orion in the city shows at least the three belt stars with the two shoulder stars visible above: the left shoulder red giant Betelgeuse and right shoulder Bellatrix, and the two foot stars below the belt including the bright right foot, the blue giant Rigel (Rigel means "foot" in Arabic). In fact, the contrast between the red left shoulder Betelgeuse and the blue right foot Rigel is an excellent way to perceive star colors which are normally not so obvious to the naked eye except for the ruddiest stars. Just know that although those two appear to be of similar brightness, Rigel is almost twice as far away at about 900 light years compared to Betelgeuse which is about 500 light years away.

Once you have found Orion, you can easily find many other constellations surrounding Orion. Standing over Orion's left shoulder is Gemini, with the twins' heads, the bright stars Pollux and Castor shining brightly. The side by side stick figure bodies lead back toward Betelgeuse. Over Orion's right shoulder is the roughly pentagonal constellation Auriga the Charioteer with its brightest star Capella. Going back to the three belt stars, you can follow them down to the southeast to the brightest star Sirius which is only 8 light years away. It is part of Canis Major, the Big Dog, and can be thought of as a dog tag. A triangular head hovers above, a front foot below, and the back angles down to a triangle making the rear haunches and tail. It is as if Orion's hunting dog is jumping up on its master. Between Gemini and Canis Major is a small constellation, Canis Minor, just two major stars including the bright star Procyon. Below Orion's feet is a group of not very bright stars forming Lepus the Hare. Going back to Orion's belt and proceeding the other direction to the northwest, the first bright star you come to is Aldebaran, the brightest star in Taurus the Bull. If you are in a very light polluted area, that may be all you see, but if you have some darkness, you will see that Aldebaran is the left tip of a "V" made of five major stars. This V shape and the many stars that are within as seen with binoculars are the Hyades, the closest open star cluster to us at about 153 light years away. This is a group of stars that all formed from the same cloud of gas and are still associated with each other. The "V" can also be thought of as the head of Taurus the Bull with each side of the V pointing up to a bright star that is the end of each horn. The right horn is made from one of Auriga's stars. Now continuing along Orion's belt in the same direction past the Hyades, you run into the Pleiades or "Seven Sisters," another beautiful naked eye star cluster, also beautiful in binoculars or with your widest field eyepiece in a telescope. It is too big to fit completely in the field of view of most telescope-eyepiece combinations. And in winter, we are blessed with yet another great binocular cluster, M44 located in the heart of Cancer the Crab, a faint constellation half way between Gemini and Leo the lion whose mane appears as an unquestionable backwards question mark (don't know if that pun was intended or not!), also known as the sickle in Leo because of its shape.

If you have a telescope, the interesting things to look at in the City are the Orion Nebula M41, not in the belt of Orion, but in the dagger or sword hanging below the belt and above the feet on the left side, appearing as a faint vertical row of three stars. The center of the dagger houses one of the best areas of star formation to be seen in the northern hemisphere and definitely the best in winter. Even in the City, you can see a few bright stars embedded in what appears to be curling glowing gas. The small trapezoidal grouping of bright stars within the nebula if seen in a telescope is known as the "Trapezium." Another place to point your telescope at low power is at the star next to Aldebaran, the next one down in the "V." Even in binoculars, you can see that what appears to be a single star naked eye is really six stars arranged in a triangle with two stars at each vertex. It is one of the remarkable geometric groupings of stars in the sky and in a wide field eyepiece, you can center the triangle in such a way that you see each of the three pairs of stars near the edge of your field of view. This is a fun thing to show passersby and is affectionately known as the "triple double."

In the City, one can always count on double stars for good telescopic views and one of the best is up in Leo the Lion. It is gamma Leonis, marked on the map with the Greek letter gamma not far from the bright star Regulus. This is a beautiful bright yellowish double that shows up easily. While you are in the neighborhood, be sure to look at Jupiter! Jupiter puts on an endless show of shifting moons and events as the four Galilean moons or their shadows pass in front of or behind the face of Jupiter. It is at these close approaches that you can literally perceive motion...fun to watch. The schedules for these events can be found on line by searching for Jovian moon events. Just a word about time: transient events in astronomy are usually expressed in Universal Time or UT, the time in Greenwich, England, on a 24 hour clock. You need to translate that time to Central Standard (minus 6 hours), or Central Daylight (minus 5 hours).

So get out there and Turn Left at Orion! http://freekindlbookdownload.blogspot.c ... orion.html
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Re: Winter from your back yard: Jupiter and the Orion vicini

Postby steve-fung » Thu Feb 05, 2015 11:36 pm

Yes, I was planning on viewing Jupiter the same night as our meeting, February 6th - should be zenith at midnight, just as you said - and I'll be looking for those tiny Jupiter moons because of SteveJ. Let's hope for clear skies, although Houston Clear Sky Chart doesn't look too promising right now...
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Re: Winter from your back yard: Jupiter and the Orion vicini

Postby steve-pinney » Fri Feb 06, 2015 10:36 pm

ok, kinda in my backyard, wife and I went the Insperity Observatory tonight (its like 4 miles from me), seeing not so great, could make out 2 bands, but the 4 moons all on one side always look great.

Orion was pretty much overhead, they had M42 on visual in the 16" and shown on computer screen using a CCD camera attached to the 20"

Naked eye saw Orion and the heads of the twins.

We waited around for awhile hoping Betelgeuse would explode but didn't happen, maybe tomorrow night.
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Re: Winter from your back yard: Jupiter and the Orion vicini

Postby mark-ferraz » Fri Feb 06, 2015 11:03 pm

Glad to see the forums getting more use :) awesome discussion going on here


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