One of many cool facts brought up in Phil Plait’s new book, Under Alien Skies is that Martian sunsets are blue!

On Earth, nitrogen scatters light randomly, with bluer colors scattering more than redder colors, so the ambient sky is blue, but when you’re looking toward the sun at a shallow angle (like sunrise or sunset), most of the blue light is scattered into the next timezone and you see red and orange.

On Mars, tiny dust particles of iron oxides (rusty dust?) reflect yellow-orange light, making the daytime sky mostly a butterscotch color…but the particles that can stay aloft in the thin atmosphere are about the size of the wavelength of blue light, so they scatter blue light forward instead of randomly. So at the shallow angles of sunset and sunrise, the sky in the direction of the sun has more blue light than the yellows that are scattered in other directions.

Essentially the same process, but reversed because of the different content of the atmosphere!

Update: I’ve finished the book, and it’s well worth reading! Here’s a link to my review!

Last Tuesday I stayed late at the office. As I was leaving the parking structure, I looked to the left for oncoming cars and saw this. I was stunned. Instead of getting on the road immediately, I parked on the side of the street to look and take a couple of photos.

It didn’t look exactly like this, of course. The photo came out too yellow, so I tried adjusting it to bring out the orange tones, until finally I just started trying all of Snapseed’s filters until I hit on this one. I was surprised by the level of detail it brought out in the upper cloud layer, and how far the crepuscular rays actually extended.

I also took a photo with my camera, which was adjusted for sunset tones. It came out a lot darker than the actual scene, but the color balance is closer. Continue reading

Buildings reflecting the setting sun Reflected sunset in the lobby

Monday afternoon I noticed the sun was still shining into my office window. This was a bit odd since my window looks out at another building, and the sun had already sunk behind it.

I looked, and it was reflecting off the building I was in, then reflecting off the building across the way.

Later that evening, I stepped out of the elevator to the sight of sunlight streaming into the lobby from the east.

Wait, east? At sunset?

You guessed it. Once again, it was reflecting off another building.

This part of Los Angeles is built on a North/South and East/West grid, and with the autumnal equinox approaching, it’s lining up just about perfectly with the shiny reflective buildings.

It also aligns perfectly with the mirrors in my car when I’m driving east at sunset. The triple sun is almost worse than driving straight at it.

It’s no Manhattanhenge, but it’s still interesting. One of these days I’ll look up the grid alignment for downtown LA (it’s diagonal) and try to recapture a moment from a few years ago, when I was in exactly the right spot for the sunset to light up all the towers bright orange. That was awesome

After a failed attempt yesterday, I was even more determined to try to spot comet Pan-STARRS tonight when it would appear near the moon. Naturally, the morning was fogged in, and the fog bank remained on the western horizon all day. I looked on Google Earth for a nearby hill with a western view and public access, and I found Fred Hesse, Jr. Park in Rancho Palos Verdes.

I arrived just minutes before sunset, and found thirty or so people lined up along the western edge of the hill with telescopes, binoculars, and cameras on tripods. It reminded me a lot of the eclipse I watched last May (also in Palos Verdes, though at a different park).

Hesse Park has a clear view to the west and southwest, with open space below, then houses, then the tops of the clouds. (I’m not sure what’s usually visible below the cloud layer). Off to the southwest you can see the northwestern section of Catalina Island. To the north you can see Malibu and the Santa Monica Mountains. Way off to the northwest you can see some of the channel islands.

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