Steve’s Virtual Planet

The Winter Hexagon

The shortened days of the winter months grant an extra chance to get out under the stars. Even with cold weather forcing star gazers to “rug up”, there are at least several objects that appear early enough in the evening such that you don’t have to brave the chill for too long into the night. A great circle of stars known as the Winter Hexagon appears overhead in the early evening forming a ring connecting a grand collection of constellations.

Starting with Sirius, the brightest star in the heavens, we can work around counter clockwise to Rigel, Aldebaran, Capella, Pollux, and Procyon. These are all prominent stars whose brightness shines through even a light veil of clouds. The circuit takes in the major constellations of Canis Major, Orion, Taurus, Auriga, Gemini and Canis Minor.

These stars range in magnitude from -1.5 with Sirius down to Pollux at mag 1.1. So, they are peeping out early and high overhead this time of year. As the night deepens, one can easily make out the figure of Orion, easily spotted by it’s belt of three stars. The ring of Auriga is usually next to become clear, forming it’s own circle of stars. The triangle of the face of Taurus slowly takes shape as the great expanse of the Big Dog about Sirius moves up into the southern sky like a big meat cleaver.

All these objects shine through even moderate light pollution. So, whether you’re in the suburbs or the country, you can practice your geometry using these fine beacons of the winter night, as in six, half dozen or the other! Enjoy!

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Full Moon - December

For December, the full moon is referred to as the Cold Moon by many North American indigenous peoples. This year, the full moon will appear on the evening of December 26. It’s the first full moon after the winter solstice.

You can start exploring how various cultures have celebrated the full moon with this article at Wikipedia. The top section of that same page has more technical details of the Moon, its phases and the basics of eclipses.

The Old Farmers’ Almanac (first printed circa 1792) web site has a detailed list of alternate names of the December Full Moon with their Native American origins. On the other hand, there is also a site called merely Farmer’s Almanac (first printed circa 1818) and it also has lots of details about alternate names for the event as well as some historical connections to the traditions of Colonial Americans.

Enjoy the Moon glow!!

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Planning on Venus - pt2

In part one of this post, I described the basic use of Sky View Cafe for planning your viewing of Venus. I hope you’ve already had a chance to see our sister planet off in the west after sunset. It’s been a lot fun showing people how Venus goes through phases, something that most folks don’t know!

In this post, I’ll describe the use of an ephemeris, which by definition, is a chart or table of times at a regular interval with the positions of objects in the sky.

Our fine friends at the Jet Propulsion Laboratory have been generating these data sets for some time, as it turns out. This data has been published on the AstroPixels website in a multi-part table where you can get all the fine details for Venus for each day. You can use this table to plan your sighting of Venus in advance (AstroPixels has charts for the sun, moon and the other planets as well ).  The columns in the list give you the main numbers - date, RA/Dec, Visual Magnitude and phase Illumination.

Once you get the feel of the empheris data layout, the next step is to get the details for Venus’ position for the day you want. You can find the azimuth and altitude numbers for each hour & minute of the day using the SkyViewCafe Sky tab. You can work the time setting back and forth, then place the pointer over Venus to get the Azimuth and Altitude on the info band at the bottom. Then, you can determine where to look by the compass bearing, then the angle up from the horizon.

Finally, I suggest making yourself a planning sheet. You can print the web page(s) but that tends to produce a lot of paper. Better yet, you can copy and paste the text from the web page into a work document. If you use the mouse to select a portion of a table, then copy, this places the text into a clipboard space you can paste into a new document of the work sheet. You can clean up the page by reducing the font size and expanding the margins so it all fits. When you have a nice neat list of items in your table, print it out as a field reference.

Happy “plan it” hunting!!

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Planning on Venus - pt1

Our sister planet Venus has returned in the western sky for Spring 2023 into July 2023. She will be with us for a number of weeks. This post will be the first one to discuss observing Venus this summer but the topic has been a favorite of mine for a while now. I first discussed the phases of Venus earlier and you might want to revisit the links on that previous post. Today, we’ll start by just finding Venus using our naked eye vision.

When planning your viewing of Venus, it’s helpful to use some kind of tool ahead of time to give you an idea where to look. You can start with a graphic view using one of my favorite tools - Sky View Cafe. For the task of spotting Venus, I first open the Sky tab, then select “Horizon - 45 Span” from the options. This reduces the size of the view of the sky, magnifying your field of view. Move the view to the west by dragging it with a mouse or by selecting a specific direction. Venus will be in the northwest for the coming weeks and arcing back up and south as the summer progresses.

Give the graphic view of the sky a try online first. You can roll the date and time back and forth and thereby determine when you will get the best line of sight from your vantage point. Also study how the twilight darkens the sky day by day. Once you get an idea where Venus will be in your field of view, then you can adjust the time and direction of this graphic view.

Good luck in your search. I’ll be back for a second post with some more suggestions. We’ll find an ephemeris so you can see the progression of Venus day by day. I’ll be working through that set of steps in part two. Using that data, we can begin to further explore the phases of Venus through a small telescope, just like Galileo did!

Updated May, 2023

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Astronomy Links

Update - The astronomy links page is now behaving. I had my highly skilled “technical staff” get on the case and they correct(ed) that little annoyance. Enjoy!

Clear skies!

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Back again. Star gazing again.

Yea, yea, yea, I know. I’ve been slack but I had to take a hiatus from all of my astronomy stuff. Nevertheless, I’m back here on Steve’s Virtual Planet (SVP)!!

The really big news from here is that Fernbank Science Center and Observatory has reopened this summer and I am back on staff finally. So, I am really glad to be back on that scene and I’ll press on optimistically and start writing updates again.

Anyhow, another autumn and hopefully more stargazing (and moon gazing, too)! Certainly more blog entries with some new series planned. Also planned is an expansion of the section on archeo-astronomy and ethno-astronomy (I’ve been researching). And I hope for a revival of an older blog I had elsewhere on Space Weather and Solar Dynamics. That will be a future focus here at SVP.

Stay tuned and check back now and then!

Clear skies! (hopefully)

Steve

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Solar Cycle 25

If you appreciate some nice sunshine, you might also be interested in how our solar system’s central star behaves over the short term. We refer to these solar cycles to describe the periodic and repeating characteristics of our sun. The changes taking place in our sun repeat over time in a roughly 11 year cycle. Hence, the term.

These cycles have have been tracked for over 400 years, ever since the early Galilean days of the Scientific Revolution. We are now in Solar Cycle 25 and the current activity of our sun is under close and detailed scrutiny. Using a fleet of satellites and solar telescopes, we watch our closest star like a hawk, in every wavelength available.

Tune in to NASA’s Space Weather monitoring site and spaceweather.com for day-to-day (literally!) updates on the fascinating life of basic, run-o’-the-mill star in our very neighborhood.

And keep on eye on Steve’s Virtual Planet for future articles on Solar Dynamics such as this trip down memory lane that links to details about the 1859 Carrington Event.

Keep shinin’!!

First published Feb 1 , 2021 Updated Sep 23, 2024

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SVC Tip #6 - Preferential treatment!

As you may have figured out by now, I have been using Sky View Cafe for quite a while. Occasionally, I find something new (or quirky) so I thought I would bring a few things to your attention.

First, I like to set the calendar tab as my default view since I want check the moon phase and to choose the day first anyhow. This can easily be done using the blue button up on the right hand corner marked “More …“. When you click it, you get … more (of course), including a set of “preferences”, Just select the little gear icon and click. The second field allows you to set the Default view. Easy.

Next, I found a couple of quirks, one being that even though there seems to be some printer settings I have had no luck with any printing feature at all. So, you may have to look for other tools for this. Finally, even though the built-in Help is really good, you may need help finding it. The help link up in the right hand pane seems broken. So, instead, use the Help ? link up in the very top center or the one in the More … button. Viola! More easy!

I hope you are enjoying SVC as much as I am. If so, check out the other tips here SVC Tip #1 & SVC Tip #2 & SVC Tip #3, SVC Tip #4 and Tip #5.

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Viewing the Lunar Straight Wall

One of the interesting aspects of observing our Moon is that many features are only visible during certain times within the full cyclic phasing of the moon. Details come and go depending on the angle of sunlight reflecting off the lunar surface and coming back to Earth. As Galileo noticed over 400 years ago, the shadow line (known as the Terminator) moves across the lunar landscape and illuminates the surface differently as it progresses across. He even used this phenomena as a tool for measuring the height of lunar features.

One such detail that is only revealed at two specific times in the cycle is the so-called “Lunar Straight Wall“. This feature is one of the best examples of a linear fault, also called a rille. When you’re looking anywhere near Mare Nubium, it’s quite prominent as an almost straight line. However, it turns out that it is easy to see ONLY on the first day past 1st Quarter or 3rd Quarter. The reason why it’s only visible around this time is because of the shadow that it casts when struck with the sunlight at just the correct angle. For the rest of the month, it’s virtually hidden because it doesn’t create a good shadow.

I have found several references online, like the one from Wikipedia in my previous post. The Lunar Straight Wall is also known by it’s Latin name Rupes Recta. I’ve included another link below from Sky and Telescope magazine with more great images of the feature. Here, lunar observing authority Charles Wood has a great article about Rupes Recta with some very fine images of this feature.

You can find it easy enough with a small telescope of perhaps 50 mm or more. That also puts this object within reach of binoculars though you’ll need to steady your hold by bracing against something or using a tripod. Use the resources above so you know where to find it and look for it on the day after first quarter or third quarter. That’s only two nights per month, making it a little more precious of a view. So, for the next two months, those dates are - March 3 and 17, April 2 and 15 and May 15, and a bonus view on May 30.

Good luck with the weather! Clear Skies! (hopefully)

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Gauging the sky with the Great Dippers

This time of year is a great time to reconnect with The Big Dipper in Ursa Major and it’s cousin the Little Dipper, in Ursa Minor. Even though Daylight Savings Time is going push dusk well into the evening, you will still be able to follow these great asterisms into early night as they climb over the trees.

As twilight progresses after sunset, the individual stars of the celestial bears gradually come into view. The brighter stars appear first of course, but the main stars in the Big Dipper are within a fairly small range of magnitude - about 1.8 down to about 2.4. In order of magnitude, you have Dubhe, Alioth, Alkaid, Mizor, Merak, Phecda. Megrez, where the handle connects to the bowl is 3.3 magnitude, but still bright enough to catch in suburban skies.

If you can see all of the Big Dipper, then you should be able to easily see Polaris at the end of the Little Dipper. It’s the brightest star in the constellation. You will also be able to see the end of the bowl of the dipper and the next brightest stars Kochab and Pherkad. The remaining stars are dimmer than 4.3 magnitude so they are much dimmer than most suburban nights will allow. But you never know your luck!

If you create a chart with these two constellations and write in the magnitudes, you will have a very useful reference to use to gauge the sky. Wikipedia has good information on all the constellations and the Celestial Bears are no exception. Follow the links below to get a lists of these stars with their magnitudes and charts that you can print to make a field reference - Big Dipper & Little Dipper. As with all the Wikipedia constellations pages, there’s also a lot of detail on the mythology and star lore of the heavens.

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