About the Planets

Venus

False-Color Cloud Patterns

This view, created using data from the Mariner 10 mission, shows clouds of corrosive acid approximately 60 kilometers above the planet's surface. (NASA/JPL-Caltech, 1974)

Amateur Photograph of Venus

Captured by amateur astrophotographer Dan Borja, this image was taken using a 150mm Shmidt-Cassegrain telescope, and is comprised of 8,000 sub-exposures. (Borja, 2020)

Gravity and Orbits

Being the second closest planet to the sun means opportunities to see Venus in the night sky are more limited than other planets, due to its proximity to the sun within the night sky. However, due to its proximity to both Earth and the Sun, Venus' changes in appearance are significantly more distinct than other planets.

As it follows its orbital path, Venus takes on a multitude of appearances due to where the line between its dark and light side fall to observers on Earth. At superior conjunction, the entire face of the planet is visible to observers, while at inferior conjunction we only see the dark side. Along with this, the planet also finds itself illuminated in a crescent shape when it is half-way between the Sun and the Earth.

To draw some scientific interest from observing Venus, pay close attention to its size and phase. Across a couple of days, the change in size should be notable to an observer looking through a telescope, the same as the levels of illumination. Its size ranges from 10 arcseconds all the way up to 64 arcseconds.

Want to explore some lesser know science of Venus? Pay close attention to the level of illumination for a few nights around the expected half-phase (dichotomy). You may be able to notice the Schroter Effect, which describes a lack of alignment between Venus' expected dichotomy and when it is really at half-phase. (Nightingale, 1967) Alternatively, watch for a warm glow (reddish or violet) on the dark side of Venus, known as Ashen light. Ashen light may be the result of airglow, thunderstorms, or the surface temperatures on Venus. (Pezzolanella, 2009)

Venus also provides notable opportunities to explore some chemistry and biology. Venus' relatively-featureless appearance to visual astronomers is actually caused by its fascinating atmosphere and characteristics as a planet. The atmosphere is comprised primarily carbon dioxide, with clouds of sulfuric acid. This thick atmosphere traps the sun's head, resulting in surface temperatures of more than 470 degrees Celsius. At the surface of Venus the atmospheric pressure is significantly greater than that of the Earth--instead being more similar to if one was 3,000 feet underwater.

Despite this harsh environment, Venus is still a notable subject to study in the search for extraterrestrial lifeforms. Recently, astronomers were able to detect phosphine on the planet's surface, which is indicative as a sign of life. While you wont be able to observe this from Earth, you can learn more by follow the link Phosphine and Life and Life on Venus.

Saturn

Saturn's Rings

Saturn's rings are comprised of particles of water ice ranging in size from smaller than a grain of sand to larger than mountains. (NASA/JPL-Caltech/Space Science Institute, 2018)

Saturn by Hubble

This image, taken by the Hubble telescope's Wide Field Camera 3, shows detail in the planet's color and ring formations. (NASA, et al, 2019)

What to look for

Saturn, a favorite for visual astronomers, is one of the best planets to observe through a small telescope. While it has a similarly nondescript surface like Venus, Saturn does reveal, through its colored bands of clouds, a look into the composition of the planet.

Dark spots (most notably at the poles and the equator) show areas of cooler air that is sinking and beginning to warm up again, resulting in drying and increased transparency, revealing darker details below the cloud-layer. Darker yellow and yellow-tan clouds are comprised of sulfur compounds and water droplets, and the white-er clouds, of rising air, are made up mostly of ammonia ice.

Make sure to look into Saturn's rings, which, while extending outwards almost 300,000 kilometers are only about 10 meters thick at most points.

The image on the right was taken by amateur astrophotographer Blueastrophotography using a 235mm Schmidt-Cassegrain telescope, a color planetary camera, and a 2x barlow.

The Moons

While up to eight of Saturn's moons can be seen with reasonable amateur equipment, expect for the 130mm Celestron GT's to limit you to the brighter moons, such as Titan and Rhea.

The most notable of the moons is Titan, which, unlike any other moon in the solar system, possesses a thick atmosphere (four times denser than Earth's) as well as interesting surface features in clouds, rivers and lakes, and rain. With an interest in biology and a bit of chemistry, Titan's Earth-like Nitrogen and Methane atmosphere likely provides valuable insight into what an ancient Earth may have looked like, as well as a valuable target in the search for extra-terrestrial life. (NASA, 2020)

The image to the left was taken by the Cassini spacecraft and published July 30, 2018.

Sources

NASA's Venus Gallery: https://solarsystem.nasa.gov/planets/venus/overview/

Dan Borja's Reddit: https://www.reddit.com/r/astrophotography/comments/euhdhx/venus_jan26/

Schroter's Effect: http://articles.adsabs.harvard.edu//full/1967JBAA...78...45N/0000045.000.html

Map of Phases of Venus by Gary Winter at SkyMarvels: https://skymarvels.com/infopages/vids/Venus%20-%20Current%20001.htm

Venus In Depth: https://solarsystem.nasa.gov/planets/venus/in-depth/

Phospine and Life: https://www.nytimes.com/2020/09/14/science/venus-life-clouds.html

Life on Venus: https://doi.org/10.1016/S0032-0633(99)00036-7

Perry Pezzolanella's Planetary Observation Write-up: https://www.mvas-ny.org/HowObsPlanets.htm

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Saturn: https://solarsystem.nasa.gov/planets/saturn/overview/

Saturn Galleries: https://solarsystem.nasa.gov/planets/saturn/galleries/

BlueAstrophotography on Reddit: https://www.reddit.com/r/astrophotography/comments/ltupv4/saturn_in_2020/

Theory of Life and Atmosphere on Titan: https://www.nasa.gov/feature/goddard/2020/nasa-scientists-discover-a-weird-molecule-in-titan-s-atmosphere

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