Mercury is relatively close to Earth, yet placing a spacecraft in orbit there is extraordinarily difficult. Here is how BepiColombo uses gravity assists, efficient propulsion and careful braking to arrive.
Learn why auroras glow green, red, blue, pink and purple, how oxygen and nitrogen create the colours, and why auroras can be more active near equinoxes.
Learn what an analemma is, why the Sun traces a figure eight over a year, and how Earth’s axial tilt, elliptical orbit, solstices and equinoxes create the pattern.
The equinox is often described as the day of 12 hours of daylight and 12 hours of darkness. In reality, the Sun’s visible disc, atmospheric refraction and latitude make the balance only approximate.
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