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How Far Away Is Mars?

The fourth planet in our solar system, Mars, is often seen as a yellow-orange star in our night skies.

It’s probably the most likely planet to be thought of as Earth’s ‘sister’ world but, actually, Mars is further away from us than Venus.

Although it resides at an average distance of nearly 142 million miles from Earth, it comes close enough to see its surface features with a simple telescope. 

Planet Mars (source)

Let’s find out how and when this happens. 

The Distance of Mars Changes Over Time 

Mars is 35.8 million miles away when it is closest to Earth and 249.1 million miles away at its furthest.

We know that Earth has an elliptical orbit around the Sun. Mars’ orbit, on the other hand, is more oval compared to Earth’s. In addition to this, Earth’s closeness to the Sun leads it to complete two orbits in the time that it takes Mars to complete one.

As a result, as both planets revolve in their respective orbits, the distance between then changes. There are times when Mars is behind the Sun, which leads to the alignment of Mars, the Sun, and Earth. At this point, known as a conjunction, Mars is as far away as it can be from Earth, at nearly 249.1 million miles (401 million kilometers).

As the distance keeps changing, Mars’ closest approach to Earth occurs when both planets are on the same side of the Sun, called opposition. At this time, Earth is placed in between our Sun and Mars, reducing the distance between planets to nearly 35.8 million miles (57.6 million kilometers)

This occurs every 26 months (two years and two months, or 791 days to be exact). During each of these times, Mars is closest to Earth and shines the largest and brightest. In fact, its apparent magnitude changes from -0.5 to -2.7 as it moves from its farthest away to its nearest, respectively. 

Changes in size and magnitude as Mars approaches opposition (source)

Since there is no clear cut answer to the distance between Earth and Mars, we can instead try to understand Mars’ closest, farthest, and average distances with respect to Earth. 

Mars’ Closest Approach to Earth

Mars is closest to Earth during its opposition when Mars is on the same side of the Sun as Earth but directly opposite the Sun in our sky. The smallest that this distance can be is 35.8 million miles (57.6 million km). The planets’ orbits make opposition happen every 26 months. 

The dates and distances for the next few oppositions are given below: 

DateDistanceApparent MagnitudeConstellation
October 13, 202039 million miles (62 million km)-2.6Pisces
December 08, 202251 million miles (82 million km)-1.9Taurus
January 15, 202559 million miles (95 million km)-1.4Gemini
February 19, 202763 million miles (101 million km)-1.2Leo
March 25, 202960 million miles (96.5 million km)-1.3Virgo

The fact that both Earth and Mars orbit in elliptical orbits indicates that there will be changes in them over time. The closest approach of the two planets was in 2018, when it was as close as 35.8 million miles, a distance that it will not repeat until September 2035.

Opposition is the best time to see Mars from your backyard. Use a suitable planetary telescope and look to its surface, through the almost non-existent Martian atmosphere, to spy its largest features.

Mars’ Furthest Distance From the Sun

Mars is furthest from Earth at solar conjunctions. The maximum distance that this can be is 249.1 million miles (401 million km)

The dates for the next few solar conjunctions are given below: 

DateDistanceConstellation
October 08, 2021240 million miles (386 million km)Virgo
November 18, 2023235 million miles (378 million km)Libra
January 09, 2026223 million miles (359 million km)Sagittarius
May 25, 2030234 million miles (377 million km)Taurus

During solar conjunctions, Mars will be on the other side of the Sun, closer to it than to Earth. It will have a separation of only 0 degrees and 16 seconds, making it impossible to observe under the Sun’s glare. This is also the time that Mars is smallest and faintest. 

Average Distance of Mars

The closest and furthest distances of Mars from Earth happen every 26 months. The average distance of Mars from Earth hovers around 142 million miles (229 million km). 

Now, it is important to note that these figures are not set in stone, but are useful approximations to remember. 

How Long Does it Take to Get to Mars?

It takes anywhere between 39 days to 333 days for a spaceship to get to Mars. Light, on the other hand, travels to Mars in 12 minutes and 42 seconds at its average distance of 142 million miles.

So far, in this article, we have learned the distance from Earth to Mars at two important points in its orbit. We can now proceed to understand how long it takes to get to the famous red planet

There are two ways to go about this. First, we will look at the time light takes to reach Mars. 

Next, we will board a spaceship (imaginatively, of course) and see how long it’ll take us to travel to the fourth planet in our solar system (we cannot travel at the speed of light, so this should be an interesting analysis). 

Let’s go! 

How Long Does Light Take to Travel from Mars to Earth?

Light travels the fastest of all known objects because it has no mass. Its speed is a whopping 186,282 miles per second. At this rate, let’s take a look at the shortest, longest, and the average time for light to travel between the two planets: 

Shortest = 35.8 million miles (57.6 million km) = 193 seconds = 3 minutes and 13 seconds.

Average = 142 million miles (229 million km) =  762.2 seconds = 12 minutes and 42 seconds.

Furthest = 249 million miles (401 million km) = 1336.6 seconds = 22 minutes and 16 seconds. 

At its average distance of 142 million miles, light takes 12 minutes and 42 seconds to reach Earth from Mars. As the planets orbit the Sun, this time varies between 3 minutes 13 seconds and 22 minutes 16 seconds. 

This also means that when you look at Mars in the morning skies, you are seeing it as it looked at least 3 minutes 13 seconds ago and maybe as long as 22 minutes 16 seconds ago! 

These calculations are if we could travel at the speed of light, which, unfortunately, we cannot. So let’s look at how long it would take us humans to get to Mars. 

How Long Does it Take a Spaceship to Travel to Mars? 

A spaceship takes around nine months to travel to Mars from Earth.

Until now, we have been focused on understanding how Mars’ and Earth’s orbits work. In order to get to Mars, considering the speed of our spaceship and the route it takes is also very important. Let’s take a look at past missions to see how long they took: 

MissionLaunch DateTravel Time (in days)
Mariner 4November 28, 1964228
Viking 1August 20, 1975304
Viking 2September 09, 1975333
Mars Global SurveyorNovember 07, 1996308 
Mars Express OrbiterJune 02, 2003201

In addition to the speed of the spaceship, the travel time to Mars also depends on the path taken.

The shortest distance is a straight line between the two planets. However, since the planets are constantly in motion, the path we follow is never so straightforward. Also, a spacecraft’s speed has to slow as it reaches Mars so that it can be captured by its gravitational field (and not fly away into space due to high speed). 

It takes between 128 days to 333 days to fly to Mars in a spacecraft.

The fastest spacecraft ever launched from Earth was the New Horizons which explored Pluto. At its record speed of 36,000 miles per hour, if New Horizons were launched for Mars, it would take 942 hours or 39 days to reach.

The shortest time a spacecraft has taken to get to Mars from Earth is 128 days (Mariner 7). The longest journey took 333 days (Viking 2).

Summary

Mars is a fascinating planet that moves closer towards and then further away from us as we both orbit the sun.

Although it might be less pretty when it is far away, its oppositions occur once every 26 months, during which it will shine seven times brighter than at its dimmest.

While we cannot hop on a spacecraft just yet to go to Mars, remembering these concepts next time you glance at the red planet will make your observations more interesting!


Written by Sharmila Kuthuner