How does the retrograde motion of Mercury compare with that of Mars?

Question

Levi Alexander · Accepted Answer

When Mars is viewed from Earth, it shows retrograde motion in the sky when Earth goes past it. Mercury never shows this motion.

Because all planets orbit the Sun in the same direction, they normally appear to move in the same direction relative to most stars from day to day (or night to night) -- namely west to east. But when Earth passes directly between the Sun and a more distant planet like Mars, the combination of our planet's faster motion plus our relatively close distance to the other planet makes that planet temporarily appear to shift westwards. If we go to Mercury, we will find Earth undergoing retrograde motion when we look back to it, every time Mercury laps Earth in its orbit. Check out the pictures shown here: https://tutor.hix.ai

Ariana Acosta · Answer

Mercury turns about the Sun faster than the Earth and the Earth is faster than Mars. Earth tends towards Mercury and Mars tends to move towards the Earth. .

The apparent opposite motion of one moving body in relation to another moving ahead is known as retrograde motion. Nearly, the orbital periods of Mercury, Earth, and Mars are 88 days, 365 days, 26 days, and 787 days. The angular speeds about the Sun are nearly #4^o , 1^o and 0.5^o#, per day.. So, Mercury turns around the Sun about 4 times as fast as the Earth and Mars turns at nearly half the angular speed of the Earth. For a further comparison of relative angular speeds, consider this: once in roughly 116 days, Earth and the faster Mercury will circle the Sun in the same heliocentric longitudinal plane. For Earth and Mars, this period exceeds two years.

Hailey Alvarez · Answer

undefined Mercury's retrograde motion is more frequent than Mars'. It occurs about three times a year for Mercury, while Mars experiences retrograde motion approximately every two years. Additionally, Mercury's retrograde motion is less noticeable due to its proximity to the Sun, whereas Mars' retrograde motion is more conspicuous due to its greater distance from the Sun.