When asked which planet is nearest Earth, many will point out Venus as being closer than Mars at certain points in their orbital path.
However, a new study has demonstrated that Mercury is our closest neighbor on average; this is because the distance between planets reduces by their average distances from the Sun.
Mercury
Mercury is the closest planet to Earth, coming in even closer than Mars at times; however, due to orbital periods being dynamic over time. Mercury typically comes first when considering distance.
Planets are in constant motion, moving around each other constantly and occasionally coming close together; but that doesn’t always indicate when they are closest – it’s actually more complicated than that!
Engineers from NASA, Los Alamos National Observatory, and the US Army’s Engineer Research Development Center teamed up to construct a computer model which calculated the average proximity between Mercury, Venus, and Mars over 10,000 years. On average they found that Mercury came closest, though sometimes Venus or Mars came first.
Stargazers will find July the ideal month for viewing Mercury as it reaches its greatest elongation and appears as a fraction of the diameter of the Moon, appearing much brighter than usual. Astronomically speaking, this phenomenon is known as an ‘inferior conjunction’ which refers to Mercury passing behind Earth on its orbit around the Sun.
Mercury is hard to spot even with a telescope during January and February due to its reduced elongation. Mercury is marked with bright streaks called crater rays created when asteroids or comets strike its surface, unleashing huge amounts of energy that not only dig craters in the ground but also crush and disperse particles of rock all across its surface, reflecting sun rays and creating bright streaks known as crater rays on its surface.
Mercury shares many characteristics with the Moon; both lack atmospheres but instead feature an exosphere composed of hydrogen, oxygen, argon, carbon dioxide and water as well as trace amounts of krypton neon and xenon that give its surface a silvery hue and regulate temperature quickly. This phenomenon gives Mercury its distinctive silvery hue as well as causing rapid temperature changes on this innermost planet.
Venus
Venus, our nearest planet, can be seen both dawn and dusk across most latitudes; however, those living further North must wait until its inferior conjunction (when it passes close to the Sun) to observe it properly. In 2024-25 it will remain visible from higher Northern latitudes until March 3rd with bi-daily observations possible at times in between (requiring an unobstructed horizon).
Southern Tropical latitude observers will experience the peak of evening apparition in mid-February, while dawn apparition will start early April. Venus will rise 30 minutes after sunset each evening and set approximately three hours after sunrise.
Venus can be seen at its most brilliant in the sky on days of maximum solar elongation, when its terminator – the line separating light from darkness on its surface – appears perfectly straight, dividing the planet in two equal halves. However, this event only occurs for several days each apparition and often lasts several hours, with observers often seeking to capture Venus at its most precise elongation point as it passes Antares, another bright red star in its path.
On October 22nd at 19 hours UT, Venus passed only 4o.6 north of Paikauhale (Scorpio). Together with Dschubba and Acrab, Paikauhale forms an impressive asterism in Northern Scorpius; Paikauhale means peanut butter in Hawaiian.
Venus will soon pass among the stars that form Libra constellation, each star bearing a name from an indigenous culture. At 23 hours UT on November 13th Venus passes within one degree south of sixth-magnitude globular clusters NGC 6544 and 6553 visible to larger telescopes.
On October 27th Venus will reach its Eastern Stationary Point when she is exactly 3o.1AU East of the Sun. In the days surrounding this event she will pass just south of red supergiant Antares and the blue-white dwarf star Algenib (Peg or Gamma Pegasi mag. +2.5). She reaches its Western Stationary Point on February 28th when it will be approximately 6deg ENE of Hebethrae (Gumbela) in Pegasus the Winged Horse as well as 15o NW of Circlet.
Mars
If asked which planet is closest to Earth, most people would answer Venus. After all, Venus is closer than any other planet in our solar system at its closest point – though keep in mind that Venus only remains here temporarily.
Engineers affiliated with NASA, Los Alamos National Observatory and US Army’s Engineer Research Development Center created a computer simulation that examined Earth’s nearest neighbors over a 10,000-year period. Their engineers discovered that Mercury spent most of its time as Earth’s closest planet instead of Venus while Mars no longer held this title.
As it turns out, which planet is nearest to Earth depends entirely upon when and how the question is asked. Venus or Mars often take this honor based on how close they come when their orbits approach ours in their closest points of approach.
At superior conjunction (when Mars is directly behind the Sun), Venus may actually be closer to Earth than Mars – only 160 million miles separate them! As planets continue their orbits, however, Mars will eventually move outward and closer than Venus to our planet.
Mars is one of the most captivating planets in our solar system and has long been studied scientifically. Astronomers have discovered that it is covered with an opaque blanket of carbon dioxide which acts like an atmosphere. Furthermore, Mars is significantly colder than Earth.
Mars can reach temperatures as cold as minus 195 F near its polar caps at night during winter, which makes navigating it extremely dangerous. Mars also features two moons: Phobos and Deimos – of which Deimos may once have been an asteroid pulled into its gravitational pull by Mars’ gravity.
The Red Planet’s surface is composed primarily of dust, rock, and some ice. It’s covered by mountains and valleys – Olympus Mons is three times taller than Mount Everest while Valles Marineris extends over thousands of miles – which make exploration difficult but nonetheless fascinating. The Red Planet offers much to discover!
Jupiter
Jupiter, our solar system’s largest planet and natural light show can be seen with the naked eye; especially its brightest face: The Great Red Spot. Located approximately 367 million miles away from Earth and visible during evening sky viewing hours. Its multicolored stripes are caused by winds blowing east-west across Jupiter; while its bright red oval-shaped storm system spans larger than our entire planet’s southern hemisphere. Known for revolving anticlockwise for 240,000 miles (650,000 kilometers).
Jupiter boasts an immense magnetosphere – a teardrop-shaped area surrounding it which reflects its own magnetic field – which protects it from solar wind – an outflow of electrically charged particles from our star that travels toward us from space. The tail of its magnetosphere extends more than 600 million miles (900 million kilometers).
Scientists speculate that Jupiter’s immense gravity may help protect Earth and other inner planets from asteroids and comets colliding into them. Jupiter can use its immense gravitational pull to swat away smaller objects – as witnessed during the 1994 Shoemaker-Levy 9 collision – or propel them out of our solar system altogether.
Astronomers have an unparalleled opportunity this month to examine Jupiter up close, as it comes within its closest approach in 59 years. The encounter occurs just prior to Jupiter’s “opposition,” when it passes directly opposite the sun in its orbit around Earth and appears larger and brighter than any star in the night sky.
People able to see Jupiter at its opposition will witness it rising in the eastern sky shortly after sunset and remaining visible through evening twilight, shining three times brighter than Sirius (the planet’s brightest star). Visibility will be improved if people search for Jupiter in an environment free from dust that also allows them to view other stars.
NASA’s Juno spacecraft, launched in 2016, is currently orbiting Jupiter, gathering information about the planet’s interior and magnetic field. Juno will pass within 222 miles (358 kilometers) of Europa, offering some of the best ever images of its surface; Europa is thought to contain a subsurface ocean which could potentially sustain life if conditions allow.