Category Archives: Ravings

What is so Super about a Super Moon?

August 10, 2014 just passed. It was the most recent Super moon. The term “Super moon” was coined by astrologers not astronomers and refers to a moon which is both full and also within 4 hours of its closest approach to earth.

The media gleefully report the super moon and show pictures of huge moons (many of which have been photo manipulated).  Here is the straight scoop on the subject. If you’re wondering whether that photo you’ve seen of the “too big to be true moon” has been doctored, we have an article on that.

Extreme SuperMoon [5_059193]

The most “Extreme” Supermoon of the Century occurred in 2012.  Here it was photographed in Yosemite approximately 15 minutes after it reached perigee.

What Makes the Moon Larger or Smaller When Seen from Earth?

Because the orbit of the moon around the earth is not circular, the distance from earth to the moon varies and thus the apparent (angular size) of the moon changes. Every lunar cycle the earth-lunar distance varies between its closest approach called perigee and its farthest distance, called apogee.  How big is the difference? The closest approach is 363,104 km (225,622 miles) and the farthest, 406,696 km (252,088 miles). 

What is the difference in apparent size?  At apogee, the moon is 22,293 km farther away or -5.8% smaller than an average moon.  At perigee the moon is 5.54% larger than the average moon. Comparing apogee and perigee moons, the difference is a maximum angular size difference of about 12%  The average angular size of the moon, by the way, is half of a degree or 30 minutes of arc. That angle is slightly smaller than the size of the nail on your little finger when held at arm’s length. Those of you with significantly mis-sized pinky nails or unusual arm length might want to find another object to measure with at arm’s length.

In short: You’d have to be a very keen observer to notice a 12% difference in size between a super moon and a “wimpy” (apogee) moon.

Because the moon is slowly spiraling away from earth eventually the perigee moon will grow smaller and smaller in apparent size until one day, we will no longer experience total solar eclipses. The perigee moon will be too small to cover the angular disk of the sun which also happens to be almost exactly one half of a degree. From that point on, all solar eclipses will be “annular” like this one in May, 2012. Had the moon been closer to the earth, this may have been a total solar eclipse.

Annular Eclipse Sequence [C_040079+5s]

 

 

How is a Full Moon Determined?

A full moon is defined as the moment in time when the sun, earth and moon are in syzygy. Syzygy is not only an interesting Scrabble(tm) word, but it defines when three bodies are in alignment. When the sun and moon are 180 degrees opposite one another relative to the Earth, we have syzygy which is the instance in which the moon is Full Moon. Many of us think of a “full moon” as that period during the month when the moon appears to be fully lit. That period lasts almost 70 hours, so we understand how reckoning a full moon as a moment in time is a bit confusing.

If you didn’t observe the August moon within 4 hours either side of when it was full, you did not see the super moon.  On the United States West Coast the super moon was not visible. Why? The moon set at 6:10 AM almost 5 hours before the moon was full. Those in Hawaii could just catch the super moon setting.  Those on the East Coast of the US had no chance at all. The whole super moon window occurred during the time the moon was not visible on the East Coast.

The Last (and Next) Visible Super Moons

If you missed the May, 2012 Extreme Super Moon (my term, photo above), you’ve missed the largest possible full moon for more than a century into the future. On May 5, 2012 fullness and perigee occurred within less than two minutes of one another.  But don’t fret.  The difference in size between the extreme super moon an the average super moon is too small to notice unless you measure carefully.  If you paid close attention you probably also noticed that the May 20, 2012 annular solar eclipse followed nearly half a lunar cycle after the May 5, 2012 super moon. That is not a coincidence! The moon was closest to us on May 5th so half of a lunar cycle away it must be farthest from us!

On August 10, 2014, full moon and perigee occurred within about 1 hour of each other. The next super moon is in September 8, 2014. The moon will not be as close to perigee at the moment when it becomes full, but the moment of full moon occurs at 9:38 PM PDT, just as the moon rises. It will be a true super moon!

Catch One Yourself

We plan to schedule a “Catching the Moon” Webinar well in advance. Stay tuned.  One complication is that the wonderful Photographer’s Ephemeris Tool will cease to work in desktop mode soon. It is being replaced with a browser version. While the tools is excellent, and we highly recommend it (and that you donate if you use it!) TPE still leaves some important bits of the puzzle unresolved – we will fill those in for you and give you a crack at our tool(s).

The moon caught between El Capitan and Half Dome - Actual size, no manipulation

The moon caught between El Capitan and Half Dome, Yosemite National Park – Actual size, no manipulation

Philosophy of Advanced Stacker PLUS

ASP14e-500

Coming soon…

Our 14e release is imminent. But after looking at our survey results and the most recently reported issues, we thought it wise to provide some hints to help you use the current software and to help you understand tradeoffs we made.

Our most commonly reported issue is something we struggled with. In an attempt to help users understand features we caused confusion. What are we talking about?  There are pop up windows: some of which should be Continued some of which should be Stopped. The only notification tool that works across all versions of Photoshop reliably doesn’t allow much customization, so when confronted with each of these dialogs, its understandable why some people click Stop when they should Continue and click Continue when they should Stop. The pop-up window below was the worst. We added highlighting to make it easy to see the difference, but we can’t use color or graphics on the actual pop-up without creating compatibility problems.  Do you notice the difference?

ASP14d_NotStop

This dialog indicates that the Watermark Alignment is not set… click CONTINUE

ASP14d_DoStop

If you stop on the first dialog, the layers needed to do stacking are not created and you will get errors the first of which is usually “Move is not currently available”

Move Not Available

Move Not Available

Once there is any kind of error it’s time to Stop and restart because manipulating layers in Photoshop is a little fragile.  The good news is the first pop-up can be turned off. The better news is that in 14e we have already turned it off for you. In fact in 14e we’ve trimmed down interaction as much as possible but still kept the awesome extra features.  Here is how to turn off the first pop-up (the one regarding Watermark Alignment) in version 14d and earlier.

Stop the Pop

Stop the Pop – disable the “Stop” step in Align My Watermark

Power of the Batch

The Advanced Stacker PLUS derives much of it’s power from two key things: Photoshop’s ability to batch process images AND Photoshop’s ability to open just about any image format on the planet.  Batch processing works because it is possible to use File -> Automate -> Batch to hurl a handful or a folder full of images at customized scripts and actions.  While Adobe Photoshop Elements has a “batch processor” there is no way to do operations other than those that are built-in to the software and that’s why ASP doesn’t support Elements.

One of the weaknesses of using Photoshop’s captive power is that it requires exploiting the tool in ways that are “allowed”.  While we like Adobe Photoshop CC, there are still many people who are very happy with older, non-cloud versions of Photoshop like CS3 or CS4.  We chose to not abandon that 35% of our customers so we support ALL CS versions of Photoshop on both Mac and PC. and that means we limit our actions and scripts to features that are common across all those versions and platforms. Readers may not be aware, for example, that while Adobe has published tools for customizing the interface, those tools have generally only supported the “latest” version of software. Indeed one of the most used tools (Configurator) has been abandoned and is no longer supported.

Another tradeoff has been in how we document our features. For example the File -> Automate -> Batch method of stacking a folder full of files is workable, if inelegant. But we use the Photoshop Bridge method of feeding the stacker and like it much more for several significant reasons.  One huge advantage of using Bridge is that you can actually see the content of the files. Another obvious advantage is that you are not constrained by what’s in your folder. If you have 29 shots from one sequence and 120 of another sequence you don’t have to split those shots between folders. And, in fact, with Bridge to select files you don’t have to use the same stacking method for all the files of one set, or have files from only one folder!

A word about 14E

As noted above, version 14E is imminent. Surprisingly the biggest obstacle has not been the additional features, the primary obstacle has been packaging and delivering the content. Windows 8.1 and Mac OSX 10.9 have gotten very protective of their machines and throw up many roadblocks to try to keep your machine safe from viruses and trojans. This means we had to invest $1500 dollars to become an LLC, get signed up for the Mac developer plan, get a Mac code signing certificate and get a code signing certificate for Windows, too! That doesn’t include acquiring a Mac or polishing the scripts and installers on each machine. Here is what the problem looks like on a Windows PC using Internet Explorer without signed code (it’s just as bad with Safari on Mac).

ASP_IE_RunAnyway

In fact, on both machines even though the code is signed (proving its provenance), you are still likely to get a warning like “This is not a commonly downloaded file”. It might be easier if we could email it to you, right? Except that Google, Yahoo and many others will not deliver an email that includes any executable content.

Both PCs and Macs have reached this point described in a Mac advertisement from 2009 that pokes fun at Vista’s intrusive safety system. Guess what… both machines are becoming like this because there are so many, uh, jerks out there eager to harm you electronically.

Our holy grail has been to create a single deliverable package that works both on a PC and on your Mac that we can document clearly, simply and as completely as possible.  That was probably too high a goal.

What’s coming in 14e?

  • Installation now is as simple as clicking.
  • EXIF data for the first image is preserved
  • New stacking mode of Ultra Streaks
  • Streamlined pop-ups to the minimum
  • Fully supports paths on both PC and Mac
  • Installation works for ALL versions of Photoshop CS you have installed on your machine
  • A price increase. But current owners will get the upgrade for free.
  • Some features we’re keeping under wraps for now.

Planispheres (Star Maps): Paper or Electronic?

Published May 29, 2014
Last Updated April 18, 2016

A topic that comes up a lot is discussion about what makes a good astronomy helper application. Whenever we suggest purchasing a paper Planisphere our critics remind us that they are not necessary because “there is a great app” to do that.

Planisphere

We take exception to the “there is an app for that” assertion… but perhaps not for the obvious reason. In fact we DO use several apps for forecasting and navigating the night sky. But ultimately we find the good old fashioned planisphere to be the most effective for most of what we want to do. We’ll make the case for a paper (or plastic) planisphere in a moment.

Why Do We Want Something Besides our Eyes?

Let’s start with determining why we want something to help us with our night sky navigation. Some scenarios to consider include:

  1. We are a beginner and we really don’t know Canis Major from Major Appliances.
  2. We have some familiarity with some of the constellations, but we want to learn more.
  3. We want to take a shot with a particular sky object behind a particular landmark.
  4. Even though we know the night sky pretty well, we still need to be able to find faint objects, or find objects in less than dark skies – the Milky Way, for example is difficult to see unless conditions are good and the sky is dark.
  5. We are going to go to an unfamiliar place with a latitude that is very different from where we normally gaze at the night sky.
  6. We want to know where to look to observe a particular phenomenon like the Geminid Meteor shower.

Can’t I Do that with an App?

It might seem that and android, iPad or iPhone app is the best tool since you can take it with you.  And that MIGHT be right except for the following significant problems:

  1. Unless you keep the app brightness really low or use it in a “dark sky mode” (usually dim red), you’ll damage your night vision making it difficult or impossible to see dimmer objects in the night sky.
  2. If you’re trying to find the Milky Way (the dense part in Sagittarius) but you try to use the app during a period when the Milky Way is not visible. No matter what time of night you enter, you won’t see the Milky Way (e.g. November through January).
  3. The representation on the app is often NOTHING like what it may look to your eye in your location. Every app suffers from this problem in one way or another. Some apps make the Milky Way in Canis Major appear to be incredulous – actually its very sedate there.
  4. You want an idea when it will be BEST to get the Milky Way aligned over your target. But on an App you will need to determine the time manually.
  5. If you mistakenly trust the app to tell you where it’s pointing you may be surprised how wrong it can be. Due to iPhone, Android, and iPad hardware limitations, a handheld app could be anywhere from close enough to off by 180 degrees!  It will be even worse if for some reason your App is configured for the wrong timezone, or the wrong GPS location.
    True story 1: I happened on a family in Yosemite, California and the dad had out his iPad pointing out to his children: “see … there is Orion”.. and over there…” but he was from Alabama and his iPad was off by 3 hours – and his compass wasn’t calibrated either so he ended up almost 180 degrees off.
  6. Dead battery. If you have to choose between enough battery to make an emergency call or figuring out your night sky… well, we recommend saving the battery.
  7. Most apps show only a fractional portion of the sky which may confuse anyone who is not already familiar with the sky.

While we freely admit that we like and use the following applications, we prefer a paper/plastic Planisphere.

  • Stellarium – FREE runs on Mac, PC and Linux.  We like it because it has excellent sky condition simulations that help give a realistic view of the night sky.  It won’t show you dim stars under bright moonlight unless you ask it to. It can also track comets and satellites. What we don’t like is that it is fidgety to configure.
  • StarMap by Fredd software for the iPhone/iPad. We like this one because it’s quite complete. It is well organized to show you, for example, what meteor showers are visible, what “dimmer” objects you can find, and has a simple interface for adjusting the sky brightness or the time of day. What we don’t like: we like to call the constellations by their scientific (and we believe) more common names.  Herdsman?  That’s Bootes. Big Dog? That’s Canis Major, thank you.  Note there are TWO versions of this App, unless you’re a serious astronomer, the less expensive one will work.
  • GoSkyWatch – admittedly we like it because we got it as a free app through Starbucks app of the week but we think its worth the price anyway! We like that it’s pretty versatile, when you point it at the sky it gives the altitude and azimuth (elevation angle and compass direction) which can come in quite handy – even though as we’ve already noted the compass direction is probably wrong! Zero in on an object and it will give you and idea what it looks like. We like that it’s Milky Way representation – while overly bright is pretty close to what it looks like. You won’t confuse Canis Major with Sagittarius, for example. It also includes a great assortment of dim objects and shows constellations with “good names” not just the “common name”. It also has a night mode to conserve your night vision.  It doesn’t have meteor showers or satellites, however.

What We Don’t Like

We’re not fond of anything we haven’t listed. Not that there aren’t better apps, but every one we’ve tried falls short in some way. Take for example, SkySafari.

SkySafari for example, is mostly a disappointment. Not only are there 12 different versions for iOS that range in price from $1 to $40, but the app doesn’t do a good job simulating the night sky, prefers to show useless images of the mythological constellations (which fortunately can be turned off) and shows a garish orange Milky Way which might be exciting to look at except that it will never look like what the app reveals.  SkySafari also doesn’t adjust for the effects of twilight or moonlight.

SkySafari does have some nice information about each object in its database, but the database is not searchable.  If you’re interested, for example in M101 you’ll have to scroll all the way to the bottom of the Messier Catalog page.  If you want to catch a glimpse of the ISS (Zarya/Space Station) you’ll have to slog through the Satellites page.

Why We Like the Planisphere

In this day and age it’s pretty normal for people to navigate by GPS, not by map or even by written instructions. It’s convenient to rely on devices. But we have driven to places and had NO idea how we got there except that “Mr. Carson” – our pet name for our British Accented “voice” – told us where to turn. In other words, we accomplished the goal of getting somewhere, but not really learning the geography, or even getting a good sense of direction. And we trust our GPS at a potential cost: the instructions could be WRONG, or dangerous, and our device might die. True story 2: we accidentally wiped our handheld GPS track when our goal was to return through a heavily fogged in trail at night – depriving us of the very bit of information that we needed!  We lived, obviously, but took several wrong turns as a result.

First we like the Planisphere because it is indeed a Map.

You can study the Planisphere day or night and observe what constellations are near other constellations.  A planisphere is in fact a rotating map. Unlike directions to grandma’s house, the appearance of the night sky changes minute by minute and season by season because of the earth’s rotation and the earths path around the sun.  While you know you can always turn left to get to grandma’s house, what you want to find in the night sky may in fact be “upside down” from what you remember 3 months or six hours ago.

From a larger map like a Planisphere you’ll discover that lining up Rigel to Betelgeuse (in Orion) and keeping straight will get you to Castor and Pollux in Gemini.  Following Orion’s “belt stars” toward the Rigel side will get you to Taurus and from there if you keeping going you’ll find the Pleiades… and so on. You’ll learn that you can navigate to the stars WITH the stars.

A Planisphere is also a Chart of Dates

A Planisphere also has a very powerful do-it-once approach to aligning things in the night sky. Spin the wheel to the sky configuration you wish and you can read around the edges every time of night over about 5 months in which the sky will appear in the same configuration!  No app we’ve seen does that!  In fact, we use the Planisphere to decide when the Milky Way will appear over our favorite waterfall or when Andromeda will be high in the night sky so we can snap it’s picture with the minimum amount of atmospheric distortion. The planisphere doesn’t tell us about the moon, but it does give us all the dates we have to work with.

Planispheres are Hard to Misconfigure

An app must have the correct location and timezone – which you may have noticed in True Story 1 can easily be quite wrong, a Planisphere is based on your local time. The only parameter you have to get right is to match your latitude with the proper Planisphere chart. If you live in San Francisco, you’ll want a chart that is valid from 30-40 degrees, not one that is 40-50 degrees and thus more suitable to Seattle residents. The most often made mistake on a Planisphere is to not subtract an hour from the time shown on the chart during daylight savings time. Some charts have the daylight savings time equivalent printed on them, but if not, just remember that during the summer if the watch reads 9 PM, you dial the chart to 8 PM.  The universe does not suddenly lurch 15 degrees when we decide to artificially set the time ahead an hour!

The one unfortunate thing about planispheres is that not all are created equal. We prefer DH Chandler’s LARGE charts because they are double sided and have less distortion than the single-sided charts. While it might be counter-intuitive to create a chart of black dots on a white background to represent the stars, it’s actually easier to read at night with a red flashlight than a chart with white stars on a black background.  You can get DH Chandler’s charts from Amazon for about $13 and from many other retailers.  If you join us for any of our events, we always have a supply on hand for our students.

Guardian of Forever