NASAのインスタグラム(nasa) - 7月25日 06時54分

Phobos photobombs Hubble’s look at Mars! When the Hubble Space Telescope observed Mars near opposition in May 2016, a sneaky companion photobombed the picture. Phobos, the Greek personification of fear, is one of two tiny moons orbiting Mars. In 13 exposures over 22 minutes, Hubble captured a timelapse of Phobos moving through its 7-hour 39-minute orbit.

This timelapse video captures a portion of the path that tiny Phobos takes around Mars. The transitions between frames have been smoothed to illustrate continuous motion. Phobos completes an orbit in just 7 hours and 39 minutes, which is faster than Mars rotates. Rising in the Martian west, it runs three laps around the Red Planet in the course of one Martian day, which is about 24 hours and 40 minutes. It is the only natural satellite in the solar system that circles its planet in a time shorter than the parent planet’s day. Hubble photographed Phobos orbiting the Red Planet on May 12, 2016, when Mars was 50 million miles from Earth. This was just a few days before the planet passed closer to Earth in its orbit than it had in the past 11 years.

Credits: NASA, ESA, and G. Bacon and Z. Levay (STScI)
#Hubble #Mars #space #science #nasa #astronomy #planet #solarsystem #phobos #telescope

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