A Sky of Fire Ice

Ice in the sky. Photo taken and provided by Joshua Thomas. Taken in Red River, NM the morning of January 9, 2015.
Ice in the sky. Taken in Red River, NM the morning of January 9, 2015. Credit: Joshua Thomas

Most people hate winter, but for those of us who watch the sky, there’s no better time to witness some of nature’s most dazzling optical displays, like the one you see here.

The image was taken by Joshua Thomas in Red River, New Mexico on January 9, 2015, at where I am guessing might be the Red River Ski resort. The arcs and halos are light passing through ice crystals, which act like tiny prisms of varying shapes. They refract and reflecting light rays into the patterns seen here. More often than not, viewing conditions only show perhaps just one or two of these patterns, but Joshua’s photo shows several rare patterns happening all at once.

Let me stipulate that I’m hardly an expert at this but with the help of the atmospheric optics site I’ve been able to identify – or at least make an educated guess – at some of these arcs. Let’s take them one at a time.

At the center is the Sun, washed out in this view., though perhaps there is a Sun Pillar formed by light reflecting off small, plate-like crystals. It is immediately surrounded by the 22° halo. These halos are fairly common, and you may have noticed them surrounding the full moon on a winter’s night. If you look closely at the photo, you’ll notice that there is a reddish color on the inside and a bluish color toward the outside. This is exactly what you’d expect to see if the light were being refracted by the ice crystals.

To the left and right of the Sun are Parhelia, or sundogs. We only see the right sundog in this photo, the left being obscured by the mountain range. Typically, these are teardrop-shaped, but sometimes they extend to form long streamers called Parhelic Circles. It looks like we have a nice Parhelic Circle going horizontally to the right. I imagine there would be one stretching outward from the left if the mountain wasn’t in the way. These circles run parallel to the horizon and can even wrap 360° around the horizon if you have a clear enough view!!

The gull wing-shaped structure is called the Tangent Arc which, as its name implies, is just grazing the 22° halo. Notice that the wingtips are connected by a “capping” arc, called the Parry Arc.

Piercing the Perry arc is a “V”-shaped sunvex Perry Arc, which is a very rare phenomenon. Sunvex Perry Arcs are caused by light passing through hexagonal column ice crystals in high and cold cirrus cloud. These ice crystals are suspended nearly perfectly horizontal in the sky,  as if that weren’t cool enough.

Surrounding the structures is what appears to be a giant rainbow. At first, I assumed this was the 46° halo, because it appears circular and seems to be about 46° across. But I learned that 46° halos are rare and typically very dim.  Now I’m thinking that this must in fact be a Supralateral Arc, which are brighter than 46° halos and show up at the same location. Supralateral Arcs are sometimes accompanied by Infralateral arcs, and at first I thought that may be what see poking up from the treetops on the left from the edge of the arc on the right at a 45° angle from the Parhelic Circle. But on further inspection, I’m not convinced that’s really what those are. Still stumped on this.

By way of illustrating my guesses, I color-coded the different arcs according to the types I think they are. Please let me know if I got any of them wrong!sky optics

Comet Lovejoy dancing in the night

Comet Lovejoy (C/2014 Q2) has been making its way higher into the northern sky these last few weeks and is nearing its peak brightness. Already demonstrating a fully formed coma and an increasingly long tail, Lovejoy has been turning up on the interwebs in some spectacular photos.

Chances are you don’t live in a location with zero light pollution and a powerful telescope, but Lovejoy is bright enough that a decent pair of binoculars will easily reveal the coma (the “head” of the comet). Here’s a pic to give you an idea of what to look for:

Comet Lovejoy, January 9, 2015 by Tom Wolf. Click to embiggen.
Comet Lovejoy, on January 9, 2015. Credit: Tom Wolf. Click to embiggen.

My friend Tom Wolf took this image last night from his home in southern Pennsylvania with his camera and tripod. Cameras are great for picking up details and colors that we cannot see with our eyes. Binoculars or even a small telescope won’t reveal a greenish color, nor will the comet appear quite so bright (unless, perhaps, you have a really nice set of binoculars). But this does give you an idea of the comet’s shape and relative “size”, depending on your binocular’s/telescope’s field of view.

Best of all, the comet is relatively easy to spot in the early evening after dark, making its way from Orion into the constellation of Taurus.  It will soon be passing by some bright stars which will make it even easier to locate in the next couple of days. Sites like Sky and Telescope and Earth Sky have some handy viewing guides. In fact, I’ve been making use of this finder chart published by Sky and Telescope to find the comet each night:

Finder chart for Comet C/2014 Q2 (Lovejoy). Credit: Sky & Telescope . Click for full size.
Finder chart for Comet C/2014 Q2 (Lovejoy). Credit: Sky & Telescope . Click for full size.

So bundle up, grab your binoculars, and find this comet. It will take a few tries but believe me, it’s a very cool feeling when you finally “bag” it in your binoculars. Enjoy Lovejoy!

Dance of the Planets

My friend Padi Boyd is an astronomer at NASA’s Goddard Spaceflight Center. She’s also a  singer, songwriter, and founding member of The Chromatics, an A Capella group who sing about, among other things, astronomy. So I was happy to hear their latest number, Dance of the Planets, got made into a nice little video. Check it out:

Dance of the Planets by The Chromatics

It’s a lovely song and a reminder of how much of our perception has  changed in such a short amount of time. Just 25 years ago, there was not a single known exoplanet – instead, we could only speculate about them and take a guess as to how what percentage of stars have planets, their number, and whether or not any of them might even have potentially habitable worlds.

Today, it’s a completely different story. We now know of more than 1800 worlds orbiting other stars, with thousands more waiting to be confirmed. We can confidently state that every star, regardless of its type, likely has at least one planet orbiting it.  The Kepler Space Telescope showed us that planets do in fact orbit other suns in their host star’s habitable zone, can have stable orbits in binary star systems, and come in a variety of sizes around stars very different than our Sun. The upcoming Transiting Exoplanet Survey Satellite will identify even more interesting targets for future telescopes, and get us started down the path of understanding what their atmospheres are made of.

It’s an exciting time to be discovering new worlds beyond our solar system, and Padi sums it up best with these lyrics:

At the dawn of the twenty-first century,
The dream has become a reality
We’re not quite as alone as we used to be,
There are planets around the stars