Tag Archives: Smog

Winter

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Southern WinterWhen this picture was taken in December, 2013, winter was approaching in the southern hemisphere of Saturn, and with that even colder season came a blue hue to some of the planet’s clouds. The color is likely caused by a reduction of ultraviolet sunlight and the haze it produces. With less haze the atmosphere is clearer, increasing Rayleigh scattering (scattering by molecules and smaller particles) and methane absorption. Both processes make the atmosphere appear blue. A similar process cause the blue color of the clouds on Uranus and Neptune.

BTW, it’s now spring in the southern hemisphere of Saturn.

Image Credit: NASA

The Supreme Court Term

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Given the Dobbs, Bruen, and West Virginia v. EPA decisions and orders in multiple cases such as Box v. Planned Parenthood and Bianchi v. Frosh, the Supreme Court appears to have decided that government by experts, including “expert” judges, must yield to democratic processes spelled out in the Constitution and that those experts should keep their noses out of the people’s personal business the Constitution shields from government intrusion.

I’ve heard it said that Conan best summarized the results thus far—

To crush your enemies. See them driven before you. And to hear the lamentations of their women—

although the Barbarian probably wasn’t a biologist.

Smog on Saturn

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north-poleThese two natural color images taken by the Cassini spacecraft show how Saturn’s north polar region has changed between 2012 and 2016. The color change is thought to be an effect of Saturn’s seasons. It’s believed that the change from a bluish color to a more golden hue is caused by the increased production of smog in the atmosphere as the north pole approached the summer solstice due in May, 2017.

The hexagon, Saturn’s six-sided jetstream, seems to act as a barrier preventing haze particles produced outside it from entering. If that’s the case, the polar atmosphere becomes clear of aerosols produced by photochemical reactions, reactions caused by sunlight, during the winter darkness. After Saturn’s northern spring equinox, the north pole polar is in continuous sunshine, and smog aerosols can be produced inside the hexagon, making the polar atmosphere appear hazy.

Image Credit: NASA

Smog on Jupiter?

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The Juno spacecraft took this image of Jupiter’s northern latitudes during a close approach 17 February, 2020. Two long, thin bands run through the center of the image from top to bottom. Juno has observed these streaks since its first close pass over Jupiter in 2016. They are layers of haze particles floating above the cloud. We’re unsure of what these hazes are made of, or how they form. (There are no known SUVs on Jupiter.) There’s been speculation that jet streams in the planet’s atmospher may influence the formation of the hazes.

Image Credit: NASA / JPL / SwRI / MSSS
image processing by Gerald Eichstädt

The Far Side of Pluto

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nh-pluto-atmosphere-infraredThis image from the New Horizons spacecraft was our first look at Pluto’s atmosphere in infrared wavelengths. The planet is backlit with sunlight coming from above and behind. The image was captured captured just after the flyby on 14 July, 2015, while New Horizons was about 180,000 km beyond Pluto. The false color image codes wavelengths around 1.25 µm as blue, 2.5 µm as red, and intermediate wavelengths as green. North in this image is at roughly 10 o’clock.

The blue band is the result of sunlight being scattered by haze particles in the planet’s atmosphere, haze which is suspected of being photochemical smog caused by the action of sunlight on methane and other molecules. These form hydrocarbons such as acetylene and ethylene which accumulate into small particles. The µm-sized scatter sunlight giving the haze its blue tint. It looks blue in visible light too. No SUVs were detected during the flyby, so this is likely a natural process. Note that Pluto is moving further from the Sun for the next century or so (it’s orbit is highly eccentric), so it is experiencing global cooling.

The whitish patches around Pluto’s limb are from sunlight bouncing off more reflective or smoother areas on its surface.

Image Credit: NASA

Saturn’s North Pole

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north-poleThese two natural color images taken by the Cassini spacecraft show how Saturn’s north polar region has changed between 2012 and 2016. The color change is thought to be an effect of Saturn’s seasons. It’s suggested that the change from a bluish color to a more golden hue is due to the increased production of smog in the atmosphere as the north pole approaches summer solstice in May, 2017.

The hexagon, Saturn’s six-sided jetstream, may act as a barrier preventing haze particles produced outside it from entering. If that’s the case, the polar atmosphere could have become clear of aerosols produced by photochemical reactions, reactions caused by sunlight, during the winter. After Saturn’s equinox in August, 2009, the north pole polar has been in continuous sunshine, and smog aerosols are being produced inside the hexagon, making the polar atmosphere appear hazy.

Image Credit: NASA

Saturn, Titan, and Changing Seasons

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This picture is a mosaic of six images—two each via red, green and blue spectral filters—combined to create this natural color view. The images were obtained with the Cassini spacecraft wide-angle camera on 6 May, 2012. The view looks toward the northern, sunlit side of the rings from just above the ring plane.

The giant moon Titan is silhouetted in front of Saturn as the planet is changing seasons. Titan, Saturn’s largest moon, measures 35,150 km across and is larger than the planet Mercury. It could have been a planet if it were on its own.

Saturn’s southern hemisphere, in its approach to winter, is taking on a bluish hue. This change seems to be caused by a reduced intensity of ultraviolet light. UV produces haze in Saturn’s atmosphere, and the increasing intensity of ultraviolet light in the hemisphere approaching summer causes the increase in haze. The presence of the ring shadow in the winter hemisphere enhances this effect. The reduction of smog and the consequent clearing of the atmosphere makes for a bluish hue. The presence of methane, which generally absorbs in the red part of the spectrum, in a now clearer atmosphere also enhances the blue. A different mechanism, the increased opportunity for direct scattering of sunlight by the molecules in the air, makes the sky blue, as on Earth.

Image Credit: NASA