Eugene Cernan

I was born just in time to say that I am a child of the Apollo era (except for arriving too late for Apollo 11, but I really don’t mind as it beats the alternative). Among my very early memories are those of the tail end of the program, and ultimately the very end with Apollo 17 in 1972 (1)Sure there was Apollo-Soyuz but it was more of a coda than an end.

That mission was commanded by Eugene Cernan, Captain, USN. Cernan was pilot of Gemini 9, Lunar Module pilot of Apollo X (which got him to within 47,000 feet of the lunar surface), and commander of Apollo 17, which closed the remaining 47,000 feet. I found this clip on YouTube which summarized Cernan’s last mission:

Until Apollo 17, every NASA astronaut was a current or former military test pilot. But this final mission included NASA’s first scientist-astronaut, Harrison “Jack” Schmidtt, a geologist. I love the genuine excitement in Schmidtt and Cernan’s voices as they find the orange rocks they were hoping to find in the Taurus–Littrow valley.

Capt Gene Cernan, USN, in the Taurus–Littrow valley, Moon. December, 1972. Credit: NASA:

“We leave as we came, and, God willing, we shall return, with peace and hope for all mankind.” — Cernan’s closing words on leaving the moon at the end of Apollo 17

Eugene Cernan was the last man to ever walk on the Moon; the last human being to ever walk on another world. And now he has left this world one final time.

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1. Sure there was Apollo-Soyuz but it was more of a coda than an end

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

The Moon and Earth

China’s Chang’e 5-T1 is the latest in a series of robotic missions to eventually return a lunar sample to Earth. Its mission is to “simply” travel to the Moon and return to Earth. Just a little run around the neighborhood. But as it was coming around the far side of the Moon, it snapped this image that should make us all stop and marvel:

The Chang'e 5 test vehicle captured this beautiful view of Earth over the far side of the Moon on October 28, 2014. Credit: CNSA
Earth over the far side of the Moon on October 28, 2014. Full size image. Credit: CNSA

You’ve got to click to see the full-sized image. It’s a perspective that’s unlike anything I’ve ever seen before. Yes, similar views were captured during the Apollo program, but nothing quite like this. Our Moon’s far side is so very different from its near side that it almost looks like an alien world. Most of the maria regions are on the near side, and thanks to tidal forces, we can never see the far side of the Moon from Earth. And yet, it’s our Moon. And there we are, on that small blue/white sphere in the distance.

I first spotted this image on the Planetary Society’s blog and it’s cool to see it getting passed around. I think images like these are crucial to our survival. Hopefully, as we continue to “grow up” as a species, we’ll better understand how finite our planet really is, how alone in the dark we really are. And how lucky we are to be alive to see it like this.