此景只应天上有 Out of this world
Gamboa Crater, Mars
It would be pretty tough to live on Mars. It's cold, dry, and the conditions are harsh. The planet's average temperature is about –81 degrees Fahrenheit, but it can get as low as –243 at the poles. But with many canyons, extinct volcanoes, and ice caps, it's beautiful to look at from afar. Most photos of the Red Planet highlight its rusty color, caused by high levels of iron oxide.
This photo shows us Mars' Gamboa Crater, but not with accurate colors. Scientists have recolored the wavelengths that our eyes can't see on their own. These added details let us see the effects of wind inside the crater, providing a perfect example of the spectacularly complex features of this planet.
太阳系的第四颗行星 Fourth rock from the sun
Red Planet Day
About 140 million miles away from Earth, the most relatable planet in the solar system orbits the sun. Mars, popularly known as the Red Planet, is the fourth planet from the sun, after Mercury, Venus, and Earth. We know more about Mars than any other planet but our own. That knowledge has been gained over centuries and has grown exponentially in recent years with the successful landings on Mars of the Curiosity and Perseverance rovers in 2012 and 2021 respectively. Today we celebrate those and other accomplishments on Red Planet Day, which coincides with the launch of Mariner 4, the first probe sent to Mars, on this day in 1964.
Mars was observed in ancient times as a bright and moving object in the night sky, distinct from the stars. Even its reddish tint was observed by the naked eye. Our curiosity was cemented. It might not be the planet closest to ours—Venus owns that title—but it seems to be the planet that most captures our imagination. The more we learn, the more we can imagine that Mars might have been just like Earth a long time ago, possessing organic life, rivers and oceans, and a much thicker atmosphere than it does today. Current conditions on Mars, while not exactly habitable, are hospitable by comparison to those on other planets, maybe the most compelling reason we're inclined to imagine that living on the Red Planet might someday be possible.
An ice cap-puccino
No, that's not a new frozen coffee drink from Starbucks; it's the southern polar ice cap on Mars. Mars is the only other planet in the Solar System with a visible ice cap, though it differs from Earth’s because it is comprised of both water ice and frozen carbon dioxide. The ice cap looks smooth here, but its surface is pockmarked with swiss cheese-like depressions caused by the seasonal freezing and melting of the Martian winters and summers. While Mars has been observed by humanity for thousands of years, it was only on August 13, 1642, that Dutch astronomer Christiaan Huygens observed the ice cap using the most powerful telescope of the day. The giant of science designed the 50x magnification telescope himself, and with his brother, produced the lenses as well.