Mars: Crash Course Astronomy #15

Summary

Crash Course Astronomy explores Mars, the fourth planet from the Sun, known for its reddish hue due to iron oxide dust. The script delves into Mars' unique geography, including its dichotomy of northern plains and southern highlands, the colossal Olympus Mons, and the Valles Marineris canyon. It discusses Mars' thin atmosphere, polar ice caps, and the possibility of past water and life. The episode also contemplates human exploration and the potential for future Martian bases, highlighting our growing understanding and fascination with the Red Planet.

Takeaways

• 🔥 Mars, known as the Red Planet, has captured human imagination through its association with war and its prominence in science fiction.
• 🌍 Mars is the fourth planet from the Sun and the outermost of the terrestrial planets, being rocky and similar in size to Earth.
• 🌡️ The average surface temperature of Mars is about -60°C, making it colder than Earth, and it is only about half the size of our planet.
• 🔴 The red color of Mars is due to iron oxide, or rust, in the fine-grained dust that covers much of its surface.
• 🌌 Mars has a dichotomy in its surface geography, with the northern hemisphere being smooth plains and the southern highlands being cratered and hilly.
• 🏞️ Valles Marineris, a massive canyon system on Mars, is longer and wider than the Grand Canyon and may have formed due to the rise of the Tharsis bulge.
• ❄️ Mars has polar ice caps composed mostly of water ice with seasonal coatings of dry ice, which sublimate in the summer to create winds.
• 🌬️ The thin Martian atmosphere, with surface pressure less than 1% of Earth's, is mostly carbon dioxide and is prone to seasonal winds and dust storms.
• 🌗 Mars has two small, irregularly shaped moons, Deimos and Phobos, which may have been captured from the asteroid belt.
• 💧 While there is no strong evidence of current liquid water on Mars, there is substantial geological evidence that Mars was once a wet planet with oceans.
• 🚀 The possibility of life on Mars is an open question, with recent discoveries of organic molecules and methane spikes raising interest in the planet's past conditions.

Q & A

Why has Mars captured our imagination throughout history?

Mars has captured our imagination due to its distinct red color, its association with the god of war in ancient times, and its portrayal in numerous science fiction novels, movies, and TV shows. It has evolved from a simple background for stories to a potential destination for human exploration.

What is the average distance of Mars from the Sun, and how does this compare to Earth's distance?

Mars orbits at an average distance of a little over 200 million kilometers from the Sun, making it the fourth planet. This places it outside Earth's orbit, and it never gets much closer to us than about 60 million kilometers.

Why is Mars referred to as the 'Red Planet'?

Mars is called the 'Red Planet' because of its reddish appearance, which is due to fine-grained, iron-rich dust on its surface that has oxidized and formed rust, giving it a butterscotch or ochre coloring.

What is the average surface temperature of Mars?

The average surface temperature of Mars is about minus 60 degrees Celsius, which is colder than Earth.

What is the significant difference between the northern and southern hemispheres of Mars?

The northern hemisphere of Mars is mostly smooth plains, while the southern hemisphere is characterized by cratered, hilly highlands. This dichotomy is believed to be the result of a massive impact from an object hundreds of kilometers across in the distant past.

What is the largest volcano in the solar system, and where is it located?

The largest volcano in the solar system is Olympus Mons, which is located on the Tharsis bulge, a huge plateau on Mars.

How did Valles Marineris, the largest canyon on Mars, likely form?

Valles Marineris may have formed when the Tharsis bulge rose up, creating the valley as a radial crack in the surface, rather than being carved by water like the Grand Canyon on Earth.

What are the components of Mars' polar ice caps?

Mars' polar ice caps are mostly composed of water ice, several kilometers thick, with seasonal coatings of dry ice, which is frozen carbon dioxide, that can be 1 to 8 meters thick.

How does the thin atmosphere of Mars affect its surface?

The thin atmosphere of Mars, with surface pressure less than 1% of Earth's, provides little protection from asteroid and comet impacts, resulting in a heavily cratered surface. It also allows for wind interactions with the surface, forming dunes and dust devils.

What are Mars' two moons, and what is unique about their orbits?

Mars has two moons named Deimos and Phobos. Both are small and asteroid-like. Phobos orbits so close to the surface and quickly that from Mars, it appears to rise in the west and set in the east. Tides from Mars are gradually lowering Phobos' orbit, and it may eventually impact the surface.

What evidence suggests that Mars was once a wetter planet?

Evidence of Mars being a wetter planet in the past includes the presence of dry river beds, dry lakes, sedimentary layers, and minerals that require water to form, as well as indications that Mars may have had oceans.

What recent discovery about Mars has raised the possibility of past life on the planet?

The Curiosity rover detected simple organic molecules in a rock sample and a brief spike in methane, which can be produced by life as well as by other geologic processes. While this does not confirm the existence of life, it suggests that the ingredients for life were present.

What are some of the challenges and considerations for human exploration of Mars?

Challenges for human exploration of Mars include the need for water, air, and food, as well as protection from radiation and vacuum. Considerations include the development of suitable technology, potential landing sites, and the idea of using lava tubes for shelter and bases.

What is the significance of the statement 'Eventually, there will be life on Mars. And it’ll be us.'?

This statement signifies the belief and ambition of future human exploration and potential colonization of Mars, suggesting that humans may one day live on the planet, transforming it from a lifeless body to one inhabited by human life.