Mars has been of interest to humanity since ancient times due to its closeness to Earth. With its reddish hue, it has even been perceived as an omen of destruction or war. However, this proximity may make it a sustainable place to live in the not-so-distant future. With that being said, just how far away is Mars?
How Do We Measure Distance in Space?
Before we talk about Mars, let’s take a look at the different measurements that astronomers use to discuss distance in space.
Miles (or Kilometers)
A common unit of measurement even here on Earth, we can use miles or kilometers to discuss distances in space as well. It actually makes sense for the few objects that are close to us, such as the Moon, Sun, Venus, and even Mars.
Astronomical Units
One astronomical unit (AU) is equivalent to 92.95 million miles (149.6 million kilometers). Uncoincidentally, one astronomical unit is the average distance from the middle of the Earth to the center of the Sun. This measurement is mainly used to measure distances within our Solar System.
Light Years
To explain distance into the far reaches of space, we need light. Rather, we use how long it takes light to travel from an object to us on Earth. Light travels at a constant 186,282 miles per second (299,791 kilometers per second) through the vacuum of space. The nearest star outside our Solar System is 4.25 light-years away.
How Far Is Mars From the Sun?
With these units of measurement in mind, how far is Mars from the Sun? On average, the Red Planet sits 142 million miles (229 million kilometers) away from our star. That’s just about 1.5 AU, meaning Mars is one and a half times the distance from the Sun as Earth is.
However, Mars has a very elliptical orbit. When Mars is at its furthest point from the Sun (called aphelion), it’s 154 million miles (249 million kilometers) away. Half a Martian year later, Mars is closest to the Sun (known as perihelion, just 128 million miles (206 million kilometers) away.
How Far Away Is Mars From the Earth?
The answer to this question is not quite as simple. Both the Earth and Mars are traveling around the Sun at insane speeds. The Earth moves at 67,000 miles per hour (107,800 kilometers per hour), while Mars travels a bit slower at 53,979 miles per hour (86,871 kilometers per hour).
Keep in mind also that Mars is farther from the Sun and has a longer orbit. Where it takes the Earth 365.25 days to make one revolution, it takes Mars nearly double at 687 days. This means these two planets are never the same distance from each other from one day to the next.
Planets at Extreme Distances
We have a good idea of how close or distant these two planets can be to each other by looking at extreme distances.
Mars at Its Closest
The closest that Mars and the Earth could ever be is when Mars is at its nearest point to the Sun (perihelion), and the Earth is furthest away (aphelion). In such an instance, the two would be 33.9 million miles (54.6 million kilometers) from each other. That’s just 0.36 AU.
This phenomenon has never happened, at least since we’ve been making notes about the cosmos. The closest we’ve recorded the Earth and Mars from each other was 34.8 million miles (56 million km) in August 2003. Due to their speeds and distance from the Sun, these two balls of rock come close about once every two years.
Mars From a Distance
On the flip side, there are times where Mars and Earth are on opposite sides of the Sun entirely. If both of these planets happen to be at aphelion at the same time, the distance between the two would be 250 million miles (401 million kilometers) apart. That’s 2.69 AU, more than seven times further than when the planets are at their closest!
How Many Light Years Away Is Mars?
With everything so “close together” in our Solar System, we don’t typically discuss distances in light-years. However, if we want to look at how far away Mars is in terms of light, it’s best to use light minutes.
If the two worlds ever pass as close together as they can come, their distance would be just 2.99 light minutes from each other. In the instance that Mars and the Earth drift to their maximum distance, they would be 22.37 light minutes apart.
How Many Years Will It Take To Get to Mars?
As you might guess, several factors come into play when considering how long it would take to get to Mars. To plan the trip, scientists have to account for planetary movement, rocket speeds, and more. They basically have to catch Mars as it travels through space at 53,979 miles per hour (86,871 kilometers per hour).
It also makes sense to use gravitational forces to help things along. Both the Sun and Moon can provide a means to slingshot a spacecraft even faster towards its destination.
Luckily, we’ve already sent spacecraft to Mars and beyond. Five rovers have already been deployed to the Martian surface. Most recently, it took the Perseverance rover a total of 204 days to travel the distance from Earth.
Mariner spacecraft 6, 7, and 9 all traveled to Mars in 1969 and 1971. Mariner 9 became the first craft to ever orbit another planet. These vessels took no longer than 168 days to make the journey. Although the New Horizons craft didn’t pass by Mars, it only took about 40 days to cross the planet’s orbit.
Can You See Mars From Earth?
Mars is definitely visible from Earth and is one of the brightest objects in our night sky. At its brightest, the Red Planet has an apparent magnitude of -2.94, only about five times dimmer than the Moon.
As mentioned earlier, Mars isn’t always close to the Earth and can sometimes appear a lot dimmer. It most frequently hangs out in the 1 to 2 range, which is still very visible but much less noticeable. The only time we can’t see Mars is when it disappears behind the Sun.
Final Thoughts
Mars may not be our closest neighbor, but we travel close to each other every two years. At times, Mars can be even closer to Earth than Venus. Although the distance varies greatly, we’ve been able to send several spacecraft there over the years. The question is, how long will it be before a human makes the journey?