The Inner Planets: Mercury, Venus, and Mars

The Inner Planets: Mercury, Venus, and Mars — page 9
THE INNER PLANETS MERCURY Venus AND MARS or a small telescope safely equipped with a solar filter are required to observe a tran sit preferably by projection of the Sun s image onto a white card The next transit of Mercury is in 2016 ORBIT AND SPIN On average Mercury orbits the Sun at a dis tance of nearly 36 million miles 58 million kilometers Like all the planets it travels around the Sun in an elliptical oval shaped orbit Mercury s orbit is the most eccentric or elongated of all the planets Its orbit is also the most tilted The plane of Mercury s orbit is tipped about 7 degrees relative to the ecliptic or the plane of Earth's orbit Mercury completes one orbit around the Sun about every 88 Earth days In other words one year on Mercury lasts some 88 Earth days The planet was named after the ancient Roman god Mercury the counterpart of the ancient Greek god Hermes Like Hermes the swift footed messenger of the gods the planet Mercury is known for the speed with which it moves across the sky The planet circles the Sun at an average rate of about 30 miles 48 kilometers per second the fastest of the eight planets 14