What is the Planet Nearest to Earth?
Venus or Mars come to mind when we think of planets nearby; their distance from the sun dictates which one ranks highest on their elliptical orbits.
However, according to new analysis published by Physics Today, Mercury actually spends the most time near Earth.
Venus
Venus is the hottest planet in our Solar System with temperatures hot enough to melt lead on its surface. Additionally, this hellish world features thick toxic clouds and scorching-hot volcanic gases erupting continuously from its core. Earth-like characteristics of size, mass and composition often compare it with Venus as they share similar traits such as proximity. Venus can sometimes even be seen brightly shining overhead as either morning or evening “star”.
Venus never comes closer than Mercury because our Solar System planets orbit it elliptically rather than circularly, meaning they only cross paths for limited periods. Venus can come close only during its inferior conjunction point in its orbit.
An inferior conjunction occurs when Venus passes between Earth and Sun, bringing their two planets within approximately 25 million miles of one another every 584 days. Over tens of thousands of years, however, Venus can only come close twice: at its closest points in orbit when closest to us and farthest away from it.
Mercury is the only other planet capable of coming close to Venus, though this happens only occasionally; even then, Mercury cannot stay close for too long as most of its orbit passes on the opposite side of our Sun than our own.
In 2012, Venus made its closest approach to Earth since 1882 and could be seen in the sky as an early morning or evening star. Venus is the brightest object in our night sky besides the Moon and can be observed going through phases when observed through a telescope. Like our Moon, Venus rotates east to west on its axis but much faster.
Mars
Mars is the fourth planet from the Sun and, like Earth, is an terrestrial planet with hard rocky surfaces suitable for walking on. Additionally, it is the driest planet in our solar system with red dusty rocks covered by an abundance of iron-rich dust particles.
As Mars circles the Sun, its orbit brings it closer to our planet at times than others, offering an excellent viewing opportunity during these close approaches. At these periods, Mars shines more brightly in our skies than when further away; opposition offers the best time for viewing; currently Mars has reached opposition this month and early October; even brighter than Jupiter at times!
Since 2003, Mars and Earth have come close in their orbits; that event provided an exceptional sighting opportunity for astronomers as well as general audiences alike. Unfortunately, such an encounter won’t recur again until 2287.
At present, Mars and Venus are in close opposition, aligned opposite of one another in the sky. Unfortunately, however, their orbits aren’t perfectly circular due to gravitational tugging from Jupiter causing irregularities which cause close approaches and separations more often than expected for viewing pleasure.
At this month’s opposition of Mars, Phobos and Deimos will be visible with binoculars or telescopes from Earth, while both Curiosity and Opportunity probes will also be studying it closely.
Mars makes for a fantastic evening skywatching target because it shines brighter and is more steady than true stars. From shortly after sunset until dawn, Mars can be easily seen rising and setting on either side of its orbit from east to west as dawn lights up the skies – you can even view livestreaming of Mars at its perigee from Virtual Telescope Project’s website!
Mercury
Mercury, our nearest planet in our Solar System, orbits it every 88 days at nearly 112,000 miles per hour. Being so close to its star means its rays heat its atmosphere generating extremely hot surface temperatures, making Mercury one of the hottest planets ever discovered by humanity.
Mercury’s fast orbit means it spends more time physically close to Earth than Venus; however, in terms of a single point in space Venus is usually thought of as being closer than her.
Scientists from Los Alamos National Lab and the US Army recently disproved this common misperception about Mercury being closer to all planets than Venus on average, not just Venus. Their new paper published this week in Physics Today details a mathematical method which takes account of all points on each planet’s orbit over time and shows that, on average, Mercury is closer than any of them on average.
To achieve this goal, they used a simulation of the planets’ orbits that took into account average times taken for each planet to reach each point, before calculating which planets were closest together at any given time – finding Mercury was closest among all of them, including Mars and Venus as well as Jupiter, Saturn, Uranus, and Neptune.
Mercury stands out in our Solar System due to its unusual circular orbit; unlike most of the other planets which follow an elliptical trajectory. As a result, Mercury tends to remain within reach of all other planets most of the time.
Earth is also the fastest planet in our Solar System to reach inferior conjunction, or its next closest point to the Sun, typically every 116 days but may take between 105-129 days depending on conditions.
Venus comes close to being our closest planet only during its inferior conjunction, since when at superior conjunction it’s far away from the Sun and cannot approach Earth as closely.
The Moon
The Moon is Earth’s sole natural satellite and fifth largest object in our Solar System, accounting for roughly one-quarter of its size and sporting a cratered surface. Unlike most planets, however, it lacks an overall magnetic field; some rocks on its surface show remnant magnetism which may indicate periods of magnetic activity in its past.
In 27 days, the Moon completes one full rotation around its axis – and one orbit of Earth – thus creating what is known as “libration”, where half its surface always faces Earth.
Many people and educational websites, as well as NASA literature, mistakenly believe the Moon to be our closest planet. This misconception stems from an incorrect understanding of how distance between orbiting bodies is measured: to know which planet is closer at any given point in space than any other, you must calculate their average distance over their entire orbits rather than simply their points of closest approach (which are often quite close).
Though its orbit differs slightly from Earth’s, it remains very nearly circular overall. Therefore, the Moon often approaches Earth very closely at perigee (its closest approach point), appearing approximately 14% larger than other times and often being referred to as a “supermoon.”
The same formula can also be used to determine which planet is closest to any given point in space, whether that’s Earth or another planet. But this method only works if both objects being compared have equal masses; otherwise one might orbit closer due to greater gravitational pull.
Therefore, Mercury currently holds the position as being closest to our home planet Earth. Mercury is by far the largest planet in our Solar System and can support liquid water on its surface; since its discovery in 2014 it has revived hope of human exploration of worlds outside our own.