The second Full Moon in a month is generally called a Blue Moon. And yes the old saying “once in a Blue Moon” is in reference to this rare event. Well… if you consider every 2 to 3 years rare. However this one will be extra special because it won’t be blue at all! It’ll be blood-red because we’ll have a lunar eclipse on our hands!
September 27th 2015 Lunar Eclipse
The lunar eclipse will be visible from most of North America, but people out West will be better placed to see it. In the East, the we’ll only get a partial eclipse as the moon sets in the early morning on Wednesday the January 31st around 6:48am EST.
If you do plan to photograph a lunar eclipse, a tripod is strongly advised, and if you are using a telescope, an equatorial mount is required. The above photo is a single frame at 2.5 second exposure and ISO400 with a Skywatcher 80ED. Yes those are a few stars popping into view during the eclipse.
Simply setting up a camera to take a series of images of the night sky can pick up a lot more than a few stars.
If you have a wide-angle lens, and live near a large city there is a good chance that some aircraft will fly into the field of view. The linear streak and alternating lights are a dead give-away of a plane having crossed the camera’s field of view. If you don’t have the alternating lights, it’s mostlikely an orbiting satellite reflecting sunlight.
Meteors are also somewhat of a common occurrence. These are easily recognized by their characteristic increasing than decreasing brightness as they burn up in the upper atmosphere. The meteor in the image above is from the Geminid shower.
The last artifact comes for outside our solar system, it is cosmic rays. The CCD or CMOS sensor of your camera works by performing an electric read-out of photons captured by the lens. Cosmic rays are high-energy sub-atomic particles that have traveled through space and managed to make it through the atmosphere down to us. The one in the photo above just happens to hit my camera sensor. As the near light-speed sub-atomic particle smashes into atoms on the sensor it looses energy, freeing up electrons which register as “light” by the CCD. Most of the time the cosmic ray will hit the sensor straight on, but sometimes it impacts at a shallow angle and causes a series of pixels to “light” up, as in the photo above.
Take time to examine your photos, you never know what surprises you may find.
With the Geminids peaking tonight and a clear sky after two nights of snow, I charged the camera battery and got a quick setup going to take some pictures of the sky. As for any nigh sky photo, both lens stabilizer and auto-focus is set to OFF and focused manually at infinity. Then found a corner of the yard shielded from stray lights and planted the tripod, roughly aiming the camera 70deg up and pointing east (the constellation Gemini was rising at 10pm).
However at -15C outside, the old battery wouldn’t last very long. I left it running for about 30 minutes, taking 20 seconds exposure at ISO 800 with a 17mm F4 lens. The camera is now thawing (covered with frost after bringing it indoors) and will wait until tomorrow before checking the pictures out.
Setup for the 2017 Geminids
In the brief moments that I was outside I caught a 2-3 meteors and one really bright one (easily visual magnitude -4). So even living in the city, the Geminids are visible and accessible to all. With my feet deep in snow I wasn’t dressed well enough to hang around in the cold wind to watch the show for long. So I hope the camera managed to capture a few.
It’s that time of the year again: the Geminid meteor shower. It is visible almost all the month of December, however the best and peak viewing, with up to 120 meteors an hour, is between December 12 and 15. It should be a good year because we are heading towards a new Moon on December 18th, so no bright moon to ruin the show.
This meteor shower is called the Geminid because the radiant (apparent direction of travel in the sky) of the meteors is centered on the constellation Gemini. However the source of the debris is not a comet like most other meteor showers, but an asteroid: 3200 Phaethon. The asteroid and orbit were discovered in 1983 and is too good of a match with the Geminids to be anything other than the source of the debris. However its makeup is closer to asteroid belt material, so it may very well be a 5km chunk from a larger asteroid, with all the associated debris.
To watch the Geminids, the best time is past midnight as the constellation will rise east around 10pm. The higher it is in the sky the better. The Geminids do regularly create fireballs: bright displays that can exhibit colour and even leave a smokey trail, so observation even in light polluted city sky is possible.
Here are some tips for the observation:
- Dress to be warm. You’ll be sitting still in the cold night. Nothing will get you indoors faster than the shivering knowing that warmth is only a few feet away.
- Lay down or recline in a chair. Standing and looking straight up is very uncomfortable and quite the strain on the neck.
- Give yourself a good 15 minutes for your eyes to adjust to the darkness If you give up after 2-3 minutes, your eyes are still adapting to night vision and will miss the fainter meteors.
- Find a spot away from sources of lights. Of course heading out of the city is best, but if you can’t, just find a spot in your backyard without the glare of street lights and neighbors’ porch lights. That also means no electronic screens to ruin your night vision.
You can also setup a camera on a tripod to see if you capture some of the meteors. Grab a short focal length, remove auto-focus and go for a 10-20 second exposure setting.
The Moon is white right? OK, OK… it only looks white because of the high contrast with the dark sky, it’s more grey. What? No? You mean it has color?
From samples returned by the Apollo missions we know that two of the main minerals making up the lunar regolith is titanium oxide (TiO2) and iron oxide (FeO) based basalts. While TiO2 is quite white and used in many household products from white toothpaste to white kitchen tiles, FeO is rust and closer to orange-brown (think Mars). On the Moon the result is a slightly blue-ish color in the areas with high TiO2, and more of a brown-red for the higher FeO and low TiO2 zones.
A normal image of the moon taken with DSRL, the different in hues is subtle as seen below.
Moon Natural Color (November 7, 2017) – Benoit Guertin
But it can be exaggerated by playing with the color saturation, and you get the image below, where various hues of blue-grey, orange and brown become apparent. The sharp boundaries between colors are caused by the different mineral make-up of the lava flows during the early formation of the Moon. Common interpretation of the age of the lunar surface is that the blue-grey areas are “younger” than the orange-brown.
Moon with exaggerated colors
Who says you can’t pull scientific information with simple backyard astronomy gear? The same technique, but with narrow-band filters is used by NASA and other space and research agencies to catalog the make-up of the lunar surface.
So if you are planning lunar prospecting for future mining rights, all you need is a telescope and a DSLR.
Some constellations are easier to spot than others. Cassiopeia with its distinctive W is visible year round in the northern hemisphere above the 34th parallel. In the image below it easily stands out from the fainter background stars.
Cassiopeia above the three line – Benoit Guertin
The five stars drawing a W in the sky are all naked eye magnitude 3 and brighter stars, and in the image above I used a layering technique to increase the color and brightness of those stars to really make them stand out.
- Duplicate your base image, and set this layer to lighten only
- Apply a blur to the top layer(about 8-12 pixels)
- Increase the color saturation and brightness. Play with the curves to brighten the bright stars, but not the background sky.
- Use a mask as required to filter out the bright foreground elements, such as light reflecting off a building roof-line in my image above.
Canon Rebel XTi
4 x 20sec ISO800
If you are able to get out of bed early before sunrise and the sky is clear, you can catch a view of our three closest planets, and if you include Earth that makes 4. Mercury was at the greatest elongation on September 12th (furthest from the Sun when viewed from Earth) which makes it a good time to spot without the glare of the Sun. But it happens that Mars and Venus are also on that same side of the Sun, making a chanced planetary alignment.
The sky map below [click for larger] shows the position of Mercury, Mars and Venus for the morning of the 16 to the 19 of September. Bright star Regulus and our Moon are also there to make this a worth-while event, especially on Monday the 18th.
Mars and Mercury will be closest on the 16th, while the 18th will probably be the most photogenic as the Moon will be a thin crescent in the middle of this alignment.