Monday, April 14, 2014

The Blood Red Moon & The Tetrad

The total lunar eclipse of 20-21 February, 2008,
as seen from one of my CCTV cameras.
The Moon is just entering the umbra. 
Before the sun rises on Tuesday, the 15th of April, 2014, the Moon will have gone through the first of four total lunar eclipses that will be visible from the Americas. There is a lot of confusion arising from this, apparently, and some misinformation floating about.
After all, it's not like total lunar eclipses are very rare events. But first, let's talk about the actual eclipse itself. 
For those of us on the east coast, the eclipse begins at 1:20 AM EDT, according to the folks at "Sky &; Telescope". Other sources list this time as closer to 2:00 AM EDT. Regardless, this is the penumbra portion of the eclipse, and for the most part is barely noticeable. The Moon really begins to darken at 1:58 AM EDT; this is the beginning of the real eclipse. Slowly, the Moon will continue to move eastward in our sky (contrary to the direction the sky's moving, in fact, and with the Earth's rotation), until 3:47 AM EDT, when it will be mid-eclipse, deep within the umbra portion of the Earth's shadow. But it is not going to be dead center in our shadow; it will be off and towards the south. This should be manifest in a southern section of the lunar disk that is brighter, the variable being cloud cover on our planet, which effects the light that shines around the edge of our planet. This light is being lensed through our atmosphere. If the Earth did not have an atmosphere, a lunar eclipse would in fact be total as long as it passed through the Earth umbra. 
The total portion of the eclipse ends at 4:25 AM EDT, as the Moon begins exiting the umbra portion of the Earth's shadow and begins getting brighter. The final partial portion of the eclipse ends for us here on the east coast at 5:33 AM EDT (earlier for us here in New England; due to the fact that we are further east, the Moon will be setting, and the Sun rising, of course). For our friends just a little further west, the entire eclipse will be visible. For the most part, though, both North and South America will see a total eclipse, for again as I mentioned, the penumbra eclipse really isn't that noticeable.
Now on to the bad information that's floating around.

Eclipse visibility chart from the
Wikipedia entry for the 15th April 2014 lunar eclipse.
(Image couresy Wikipedia)
First, unlike a solar eclipse, it doesn't matter where you are during a lunar eclipse. From Boston, you will see the same part of the eclipse as Buenos Aires. This is because we are looking at the shadow being cast, not from it. 
Second, there is no guarantee that the Moon will turn just "blood red". There is a good chance that it will, but remember what I mentioned up there; the real variable is going to be cloud cover around the Earth's atmosphere. The more clouds, the more likely it will be darker. The fewer, the brighter. In short, it could go from blood red to dark chocolate. 
Finally, there is much ado about this eclipse and the "tetrad" that it marks the beginning of. A "tetrad" in this case refers to a series of four lunar eclipses spaces at six month intervals. Usually, it is not uncommon for there to be three lunar eclipses over a one year period. This tends to be the most common pattern, a "triple". Tetrads are not as rare as it would seem, in fact. The last tetrad occurred in 2003-2004 (not quite eleven years ago). What's unusual about this tetrad is that it will be visible from the Americas. 
So, what does this mean?
Absolutely nothing.
There are people who are desperately looking for some sort of meaning in this, yet in reality one does not exist. Have historic events occurred near or around these events? Certainly; after all, really triples, tetrads and just good old lunar eclipses are not that uncommon. As one of my high school teachers used to say "correlation does not equal causation". In other words, they are coincidences, and nothing more. We seek answers, we look for them hard enough and think we see patterns. It is our desire to find those patterns that actually produces them. 
If you get a chance, try and stay up late to catch this wondrous event. For my friends further west, you won't need to stay up nearly so late. For us here in the east, it looks like an all nighter.
And sadly, it's looking increasingly like a no-go here in Connecticut. Clouds are rolling in, and the rain is coming. 
We'll see.

Saturday, April 12, 2014

Solar "Reflections", Part 2

As the warmer weather gets underway here in New England, I turn my attention to more things astronomical. For the first time in weeks, I no longer fear being exposed to bitter cold. While there may be plenty to do at night, I have turned my attention to solar astronomy. 
As mentioned on my entry for the 1st of this month ("Solar "Reflections""), I decided to play with an alternate method of viewing the Sun, and the initial results showed promise. One thing I failed to mention with regards to these recent attempts is that on the 29th of January of this year, there was an chance alignment that produced a solar image on the wall between the foyer and the half bathroom. It wasn't the sharpest of images, but was clearly the Sun.

I decided to make a "screen" (a cardboard box top) to see what type of image could be gleaned. 

It turned out the the source was light coming through the kitchen window and passing between the freezer and refrigerator doors and handles. 

It wasn't much of a pinhole, but it was just enough to produce an image. It was just sharp enough for me to make a simple animation of the Sun heading down.

Now on to the current work.
After my initial foray into pinpoint reflection this month I decided to try again, but this time setting going even further. Additionally, I made a dedicated solar filter and Hartmann mask for my Celestron FirstScope, and have been undertaking a series of observations with that as well. But I wanted to see to what limits pinpoint reflection could be taken. 

As I had already set up for my daily solar session, I felt that it was also the best time to try for a projection into the house. With the Sun at such a high angle, it was guaranteed to be much brighter, and therefore able to provide that much more contrast. It was almost 13:00 EDT, and the Sun rode high.
I chose to set up, as I had before, on the back porch, taking advantage of the recently unpacked table to mount the pinpoint mirror. As I mentioned in the previous piece, this is a small fragment of a first surface mirror, but what is important to note is the size; not quite 5 mm square. In my first attempts back in the autumn of 2013, I had reduced that area to a point 3 mm in diameter. Since then, the paint has come off. While we may have lost some detail, we gained contrast. 

I set up my drawing pad and easel on the dining room table. Total distance between the mirror and the paper was perhaps 9 meters (30 feet). The resulting image was around 125 mm (5 inches), but a measurement wasn't taken. The solar disk showed, but didn't provide enough detail.

For my second attempt, I slowed my camera's shutter speed. This allowed for a little more contrast. Something began to show up. The third attempt was pretty much the same.

It was at this point that I decided that what was really needed was more distance between the mirror and the screen. I chose to go another 2.4 meters (8 feet). This resulted in the easel being set up straddling the kitchen sink. Here, the details started to become a little clearer. Sunspots were beginning to become visible. 

After adjusting the the image's contrast and light levels, the sunspots in the Sun's northern hemisphere became very visible. The small group coming around the Sun's western limb was even there, albeit faintly. 

North is to the left in the projected images.

Compare this to the official Space Weather image for today.

By this time, high altitude clouds began making rolling in, so I put away my gear and waited. 
At a few minutes before 16:00 EDT, I decided to go even further afield, this time into the yard beyond the porch.

My "screen" was taped to the wall in the living room. Overall distance was now about 18 meters (60 feet). The projected image was around 200 mm (8 inches). There were still some high altitude clouds, but not as bad. Not surprisingly, some work with the image still needed to be done. While some of the contrast was lost, after the image was worked, the sunspots once again showed very clearly. They were, however, noticeable to the naked eye.

Perhaps what is really needed is a lot of distance and a very dark room into which the image is projected. No doubt larger sunspots would show even better. 
Still, I think we can call this little experiment a success. If anything, it was fun.

Tuesday, April 01, 2014

Solar "Reflections"

1st April, 2014. 
Today was the first really nice day we've had since November. The temperatures weren't terribly high still, just 49° F (9° C), but in the sunlight, it feels so much better than the winter we've had. It was also remarkably clear today, with that wonderful Sun shining like mad up there in that sapphire sky.
In other words, it was a perfect day for solar astronomy and a little experimentation. 
Back in early fall of 2013, I took a small chunk of broken first surface mirror I had and attached it to a piece of cardboard, and played around with solar pinhole mirror projection. This is the opposite of regular pinhole projection, since there is no hole, instead just a very small reflective source. My test last year weren't perfect, but they showed that yes, a solar disk could be projected. The problem was that I was projecting the image onto a screen outside, where it was too bright. 
For today's experiment, I chose to cast the reflection into the condominium, and with much better results. 
The mirror and its base were taped onto the head of one of my tripods, in a manner that allowed it to be easily aimed (much like a camera, in fact). 

The tripod was then carried outside onto the back porch. It was shortly before noon, and the Sun was fast approaching the meridian. It took a little work to get it aimed. I chose a spot on the dining room wall, next to the large decorative clock that hangs there. This allowed for an image that was a little over 5" (125 mm) across). This was perhaps 25 feet (8 meters) from the mirror. 

It worked, though the resulting image was not as sharp as I would have liked. 

This is the trade off. You can choose sharpness over contrast, making the pinhole (or in this case the reflective surface) smaller. The resulting image would be darker, however. For today's experiment, I chose contrast over detail. 
Amazingly, after the images were pulled and processed, I was surprised to discover that the largest patch of sunspots on the main disk, group 2021, was faintly visible in the image. A little sharpening, and you can sort of pick them out. 

In this projection of the Sun, north is to the left.
The Sun, 1st April 2014, courtesy
Certainly, the method can be improved, but it is severely limited. You will never have the acuity that a lens system will provide. As a safer method for observing things like eclipses, transits and larger sunspots, this method should be sufficient.
I do wonder to what extreme it could be taken. Maybe that will be a "project" for the future.