Colors Of The Polar Night

The Carina Nebula.

Comet meets cluster by europeanspaceagency

Nightfall

I feel my favorite Sci-Fi story of all times must be Isaac Asimov's 'Nightfall' (SPOILERS ahead btw) (the title in my language is even better, "And Darkness Shall Come").

To quickly summarize from memory, the story is set on a planet where people live in constant daylight because their homeworld is illuminated by one of six suns at all times. By the time of the narrative, they have reached an industrialized, roughly early 20th-century style civilization.

A prophecy speaks of a cycle where the planet will fall into complete darkness, and now scientists have discovered that it is not just a fairy tale - apparently, one day soon another planet is gonna block out all the suns for a period of about 12 hours.

Disturbingly, another part of the prophecy is confirmed as well - archaeologists discover that the planet's cities have been burned to the ground every time the darkness came, resetting civilization, and only returning to the old level of development after thousands of years.

The prophecy says that people will go mad in the darkness, when they look up to the sky and the stars appear.

Now, scientists and governments are alarmed, but not panicked. They look at their technolgical progress and understanding of the universe, and they are confident their civilization will not fall like the others. They know their people are literate, the current level of knowledge about the cosmos is widespread - including the theory that there might even be more than one solar system.

Electrical lights exist, but on this planet they only have niche applications in things like mining operations and bunker construction. Outfitting entire cities with them is not feasible on short notice, and also considered a waste of resources - 12 hours without sunlight should be perfectly survivable for an advanced and enlightened people.

There are experiments to simulate the effects of the darkness on the psyche. One scientists sits in a dark room with a few dozen holes in the ceiling, to simulate these fabled "stars", and declares it's manageable.

Then the big day arrives - or rather, ends.

The suns disappear, and darkness falls across the land.

And people look up, and they see this

And their civilization ends within 12 hours.

I tried to draw the moon in 3D @joaovitornart

Welcome to….DEVONIAN PARK. Please don’t tap the glass (the dunks are very sensitive).

I had a really stupid idea and had to paint it for a friend.

Ten interesting facts about Uranus

Like the classical planets, Uranus is visible to the naked eye, but it was never recognised as a planet by ancient observers because of its dimness and slow orbit. Sir William Herschel announced its discovery on 13 March 1781, expanding the known boundaries of the Solar System for the first time in history and making Uranus the first planet discovered with a telescope.

Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. Uranus is similar in composition to Neptune, and both have different bulk chemical composition from that of the larger gas giants Jupiter and Saturn.

(The five largest moons of Uranus) Like all of the giant planets, Uranus has its share of moons. At present, astronomers have confirmed the existence of 27 natural satellites. But for the most part, these moons are small and irregular. 

Uranus’ moons are named after characters created by William Shakespeare and Alexander Pope. These include Oberon, Titania and Miranda.  All are frozen worlds with dark surfaces. Some are ice and rock mixtures.  The most interesting Uranian moon is Miranda; it has ice canyons, terraces, and other strange-looking surface areas.

Only one spacecraft in the history of spaceflight has ever made a close approach to Uranus. NASA’s Voyager 2 conducted its closest approach to Uranus on January 24th, 1986, passing within 81,000 km of the cloud tops of Uranus. It took thousands of photographs of the gas/ice giant and its moons before speeding off towards its next target: Neptune.

Uranus has rings: All the gas and ice giants have their own ring systems, and Uranus’ is the second most dramatic set of rings in the Solar System.

Uranus makes one trip around the Sun every 84 Earth years. During some parts of its orbit one or the other of its poles point directly at the Sun and get about 42 years of direct sunlight. The rest of the time they are in darkness.

All of the planets in the Solar System rotate on their axis, with a tilt that’s similar to the Sun. In many cases, planet’s have an axial tilt, where one of their poles will be inclined slightly towards the Sun. But the axial tilt of Uranus is a staggering 98 degrees! In other words, the planet is rotating on its side. 

Uranus is approximately 4 times the sizes of Earth and 63 times its volume.

Uranus is blue-green in color, the result of methane in its mostly hydrogen-helium atmosphere. The planet is often dubbed an ice giant, since 80 percent or more of its mass is made up of a fluid mix of water, methane, and ammonia ices.

Uranus hits the coldest temperatures of any planet. With minimum atmospheric temperature of -224°C Uranus is nearly coldest planet in the solar system. While Neptune doesn’t get as cold as Uranus it is on average colder. The upper atmosphere of Uranus is covered by a methane haze which hides the storms that take place in the cloud decks.

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Images credit: NASA/ wikipedia

Pickering’s Triangle

Dear @thought-cafe team, we need more Crash Course Astronomy episodes! Can you please do a Season 2? Dr. Phil Plait is awesome, and we miss him!

If you’re excited about the juno news today, sink your teeth into a Crash Course episode that’s all about Jupiter! 🔭  https://youtu.be/Xwn8fQSW7-8

I love the fact that a group of crows is called a "Murder" and a group of ravens is a "Conspiracy"