Yes, the planet Mars is visible to the naked human eye, often appearing as a bright, reddish-orange point of light in the night sky. Mars orbits the Sun like Earth, meaning its visibility changes dramatically depending on its position relative to us. Spotting Mars requires knowing when and where to look, as its apparent brightness fluctuates more than any other planet visible without aid.
The Science Behind Mars’ Brightness
The visibility and apparent size of Mars are dictated by the ever-changing distance between Earth and Mars as they follow their orbits around the Sun. Since Mars’s orbit is the next one out from Earth’s, the distance varies significantly, ranging from about 35 million miles to over 250 million miles. This variation causes the planet’s apparent magnitude, or brightness, to fluctuate widely, more so than any other planet.
The peak viewing opportunity occurs around “opposition,” which happens when Earth passes directly between Mars and the Sun. During opposition, Mars is at its closest point to Earth, making it appear largest and brightest in the sky. At its brightest near a favorable opposition, Mars can outshine all stars and even Jupiter. Away from opposition, Mars can fade considerably, sometimes becoming one of the dimmest naked-eye planets.
Practical Guide to Locating Mars
To find Mars, look for its distinguishing characteristic: its reddish or apricot-colored hue, caused by iron oxide dust on its surface. This color sets it apart from the white or blue-white light of most stars and other planets like Venus or Jupiter.
Mars, along with the other planets, the Sun, and the Moon, travels along a narrow band in the sky known as the Ecliptic. This means Mars will never be found high overhead or near the pole stars, but rather in the southern part of the sky (for northern hemisphere observers). When Mars is visible, the best time to look is usually around midnight during opposition, as it is high above the horizon. Consulting an astronomical app or website can provide the exact rise and set times for your location and the current direction to look.
How to Distinguish Mars from Stars
A common confusion for new observers is telling a planet from a distant star, but the difference is noticeable with a careful look. Stars twinkle because they are so far away they appear as a single point of light, which is easily distorted by turbulence in Earth’s atmosphere.
Planets like Mars, being much closer, appear as tiny disks rather than points of light, even to the naked eye. This slight apparent size means that light rays coming from different parts of the planet’s disk average out the effects of atmospheric distortion. Consequently, Mars presents a steadier, non-twinkling light compared to the shimmering pinpoints of the background stars. Over several nights or weeks, you can observe that Mars changes its position relative to the fixed background stars. This movement gave rise to the term “planet,” which means “wanderer.”