On April 8, 2014, we will have Mars opposition
All the planet in our Solar system orbit the sun. Earth and Mars are not exception. But Earth is closer to the sun than Mars and makes a full orbit faster. In fact, while Earth makes 2 orbits, Mars makes 1 orbit around the sun. So, sometimes the two planets are on opposite sides of the sun, but other times they are on one side of the sun and are relatively close to each other.
What is an Opposition?
Mars Opposition is when Mars and the Sun are on directly opposite sides of Earth. The three celestial bodies are in one line and Earth is in the middle.
What does this mean practically for us on Earth?
When the sun sets on the west, Mars rises in the night on the east. Mars stays the whole night on the night sky and when the morning comes, the sun rises on the east and Mars sets on the west. That’s it! When Mars, Earth and the Sun are in line, we say that we have Mars opposition.
When Can an Opposition Happen?
Mars oppositions happen about every 26 months and they can happen at every point in Mars’s orbit.
Note however, that this doesn’t mean that Mars and Earth are at its closest during this time! This is because the two planets don’t have circular orbits, but elliptical!
About every 16 years, oppositions occur within a few weeks of Mars’s perihelion. (Mars perihelion is the point when Mars is at its closest to the sun. Remember, planets rotate in elliptical orbits around the sun. Mars’s orbit is a little bit more elliptical than ours on Earth.) Such an opposition happened in 2003 when NASA launched the two Mars Exploration Rovers to Mars.
As we said, an opposition can happen in every point of Mars’s orbit and an opposition during Mars’s perihelion can occur about every 16 years. If Earth’s and Mars’s orbits were stable (meaning not changing over time) that would be the closest they could get, but the orbits of the planets change a little bit with time due to gravitational tugging. Gravitational tugging is when other celestial bodies change the orbit of Earth and Mars with their gravity. Jupiter, for example, influences a lot the orbit of Mars. Also, Mars and Earth orbit the sun in slightly tilted orbits according to each other. Because of all additional factors, the 2003 opposition was the closest distance between Earth and Mars in … stay sit for this … almost 60,000 years!!!
Oppositions in the Future
Read this – As we said, Mars’s orbit is more elongated than Earth’s is, which means that it’s perihelion and aphelion is greater. (Aphelion is the point in the celestial body orbit where it is farthest from the Sun.) Over a huge amount of time during the centuries, the orbit of Mars gets even more elliptical (elliptical = elongated), which means that during its aphelion, it will get even farther from the Sun and during perihelion, even closer to the Sun.
So, future perihelion oppositions like the one in 2003 will bring Earth and Mars even closer than the one in 2003! The next closest record will be on August 28, 2287! Maybe at that time, it won’t matter so much to NASA and Humanity and we won’t have to rush to send 2 rovers at that point (as we did in 2003 with Spirit and Opportunity). Maybe at that time, transportation between mother Earth and Mars will be something common and many people will live on Mars!
Until then, clean up your telescopes and go outside around April 8 to watch the orange dot in the night sky!
by Tihomir Dimitrov
The Human Adventures in Space Exploration – 04.2014
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