Ancient stargazers were fascinated by the planets -- the mysterious lights that seemed to wander through the
fixed stars. They watched the planets closely and learned their motions so well that they could predict
where each planet would be for any night of the year.
How well do you know the motions of the planets? By watching the videos below you'll gain a good understanding
of their motions for 2022. To get the most out of the videos, here are some things to know first:
1️⃣ Planets move along a path in the sky called the ecliptic.
The ecliptic is an arc in our sky that stretches from the western horizon to the eastern horizon and wraps around
the Earth. It marks the plane of our solar system upon which the planets orbit the sun. In the videos,
it appears as a yellow line.
2️⃣ Each planet moves at its own speed.
The closer a planet is to the Sun, the faster it must go to not fall into the Sun by force of gravity. In the videos,
you'll see huge differences in the speeds of the planets
3️⃣ Planets move from west to east... most of the time.
All the planets move in the same direction around the Sun so you may be surprised to learn that every planet
appears to reverse direction for short periods. This phenomenon, known as retrograde, baffled
ancient stargazers. If only they had realized that Earth is in motion too. Whenever Earth passes a slower planet or
is passed by a faster one, the other planet appears to move backwards. In the videos, when you see
a planet reverse direction you'll know that it is only an illusion. Also, for the outer planets, retrograde is centered on
opposition -- the best time for viewing the planet.
4️⃣ The Moon is the fastest 'planet'.
Ancient stargazers called the Moon a planet because it also appears to move along the ecliptic. In the videos, you'll
see the Moon as a 'flash' of light as it passes each month.
5️⃣ Planets are visible for part of every night except when they are close to the Sun.
In the videos, you'll see the planets getting close to the Sun. When this happens, the planet will have no visibility at
night or will be limited to short periods of time right before sunrise or after sunset.
The Motions of the Planets in 2022
Mercury
Notice how incredibly fast Mercury is and how it is never far from the Sun. Because of this, it is not visible at night
-- only at dusk or dawn for short periods. Best viewing is when it is furthest east (left) for dusk viewing
or west (right) for dawn viewing. These times are known as maximum elongations. The best elongation for 2022 will be around the end of April because Mercury will also be high above the ecliptic making it higher in our sky and easier to see.
Venus
Compared to Mercury, Venus can appear much further from the Sun. This means that it can be visible for hours at
night. When it is east (left) of the Sun, it is visible after sunset as the Evening Star. And when
west (right), it is visible before sunrise as the Morning Star. What will it be for most of 2022? Notice that
this changes in December.
Sun
Why is the Sun in this list? Like the planets, the Sun moves along the ecliptic. However, its motion is an
illusion -- it's due to Earth's orbit around the Sun and not its own. It should be no wonder then that the Sun takes
exactly one
year
to
orbit the ecliptic. It starts and ends in Sagittarius and spends about a month in each
constellation along the way. In the video, notice how the Sun doesn't veer from the ecliptic like the planets do but
always is centered on it. This is because the Sun defines the ecliptic.
Mars
The best viewing of Mars occurs when it is in opposition with Earth because Mars is at its closest. This
happens every 26 months and will occur in 2022 on December 7. In the video, notice how Mars is in
retrograde in December -- a sure sign that Earth is passing Mars in their orbits around the Sun. This will be the
best time to try to glimpse the enormous volcanoes and canyons on Mars as well as its polar ice caps.
Jupiter
Jupiter, being so far from Earth, is noticeably slower than the planets above. The best viewing will be in late
September when it is in opposition with Earth. In the video, notice how Jupiter is in the middle of its retrograde
motion in September. This will be a great time to view its bands and the Great Red Spot.
Saturn
Saturn is even slower than Jupiter and will spend all of 2022 in Capricornus. In the video, see if you can figure out
which month opposition is. This will be the best time for viewing this incredible planet and its system of
rings.
Uranus
This elusive world is the most distant naked-eye planet. Ancient stargazers never realized it was a planet and it is
easy to see why in this video -- it moves so very slowly. Notice how much of its forward (eastern) motion
seems to be undone by its retrograde motion. It will take until 2025 to pass out of Aries and into Taurus.
Neptune
Neptune is the only planet that cannot be seen naked-eye -- it requires optical aid like a binocular or telescope. In
the video, notice how its motion is barely perceptible. Even its retrograde motion as Earth passes is
small. It will take until 2040 to pass through Pisces and into Aries.
