Jupiter’s moon Ganymede is the largest and most massive of the Solar System’s moons. It has a mean radius of 2634.1±0.3 km (about 1636 miles, 0.413 Earths). For comparison, our Moon’s radius is 1,737.1 km (1079 mi). What if Ganymede was the Earth’s second moon? How would it look in the sky, if it was at the same distance as the Moon?Continue reading What if Ganymede was the Earth’s second moon?
On 11 January 1672, the Fellows of the British Royal Society were treated to a demonstration of Isaac Newton’s reflecting telescope, which formed images with mirrors rather than with the lenses that had been used since the time of Galileo. Afterward, the fellows hailed Newton as the inventor of this marvelous new instrument, an attribution that sticks to the present. However, this linear historical account obscures a far more interesting, convoluted story. Newton’s claim was immediately challenged on behalf of two other contenders, James Gregory,
Back in December 1990, during its flyby of Earth, NASA’s Galileo spacecraft, which studied the planet Jupiter and its moons, as well as several other Solar System bodies, pointed its instruments towards Earth, at the urging of Carl Sagan. And, it has found evidence of life on our planet. This can be a key to detect vegetation on exoplanets – which is a key to a possible i
In a paper published on Nature, researchers wrote “The Galileo spacecraft found evidence of abundant gaseous oxygen, a widely distributed surface pigment with a sharp absorption edge in the red part of the visible spectrum, and atmospheric methane in extreme thermodynamic disequilibrium. Together, these are strongly suggestive of life on Earth.”Continue reading Earth can be a model for detecting vegetation on exoplanets
Earth, our beautiful blue planet. It is the third planet from the Sun, but above all, it is our home, the only astronomical object known to harbor life. Here are the best quotes about Earth.Continue reading Earth Quotes – 10 Best Sayings about Earth
It’s one of the basic Newton laws: how fast something falls due to gravity is determined by a number known as the “acceleration of gravity”, which is 9.81 m/s2 at the surface of Earth. The acceleration of gravity, shortly “a” means that in one second, any object’s downward velocity will increase by 9.81 m/s because of gravity. The gravity accelerates everything at exactly the same rate.
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