Planets are generally the brightest objects in the sky, and they’re easy to spot since they don’t twinkle like stars. All planets orbit the Sun, and their orbits are all in the same plane, which means they all follow a similar route in the sky, near to the ecliptic. At certain times, some planets, such as Mars, appear to move backward along the ecliptic, a phenomenon known as retrograde motion.
It’s not a planet if you detect a bright object far from the ecliptic (in the constellation Cassiopeia, for example). Use a planet-finding chart or ephemeris to figure out which planets are visible on any given night. (see Stargazing Tools).
Table of Contents
Mercury
Mercury, like the Moon, has a highly cratered surface, but you won’t be able to see it clearly—it’ll just seem as a brilliant dot.
- It is located closest to the Sun. Mercury is only seen during twilight, either after sunset or just before sunrise, when it is 28 degrees from the Sun.
- What you’ll need to see it: You can see Mercury with the naked eye in good conditions, but you’ll normally need a telescope. Make sure there are no barriers in the way of the Sun’s path down the horizon.
The planet Mercury has the distinction of being the smallest planet within our solar system, being only 40% as large as the Earth. With a name derived from Roman mythology due to Mercury’s rapid rotation around the sun, the planet travels through space covering almost thirty miles every second. It is also the closest planet to the sun at just over twenty-eight million miles away, making it by far the warmest planet.
A full day spent on the surface of the planet would calculate to around one hundred seventy-six days on Earth; and since it takes fifty-nine days to complete one full rotation around its axis only two actual sunrises would be visible each year. Although the Sun would appear twice as large if standing atop the planet Mercury, the sky would appear black because of the thin atmosphere.
Since Mercury is the closest planet within our solar system to the Sun, it has by far the hottest surface temperatures ranging from three hundred to eight hundred degrees Fahrenheit, with the dark side of the planet reaching temperatures as low as -300 degrees because of the lacking atmosphere to retain warmth.
This is the biggest swing in temperatures present within our solar system and is an interesting study since the surface would actually be hot enough to melt most metals during daylight hours. The sunlight from Mercury’s surface would appear 6.5 times more intense than we experience on Earth, which means even if a person would somehow survive the extreme heat and lack of oxygen they would be virtually blinded within the brightness.
It is believed that just after the Big Bang and the formation of the Mercury, the planet received massive damage from comets and, meteors, and asteroids. Although the planet is one of only three within our solar system that is perfectly symmetrical, the smooth rocky surface is riddled with craters showing extensive cosmic damage that occurred up to 4.6 billion years ago.
The largest of these craters stretches over eight hundred miles across Mercury’s surface and the appearance is much like our own moon for comparative purposes.
Sunlight never reaches the polar caps of Mercury and ice has been discovered there, but the lack of a functional atmosphere would make life on the planet’s surface impossible. The solar winds sweep away what little atmosphere is present on Mercury almost continually, which means it has little protection from damaging objects in space.
The atmosphere is constantly renewing and creates a vacuum like effect so gravity could not be present for extended periods of time. Its iron core generates a magnetic field thought to be less than one percent as strong as what is found on Earth, making the planets similar in overall interior composition.
The reflection qualities of Mercury are similar to our own moon, sending only about six percent of the light that strikes the surface back into space. Because of these qualities Mercury is difficult to view from our planet, and the best times to view the planet would be around sunrise and sunset.
With the assistance of a telescope Mercury can be witnessed going through phases much like we associate with the moon in regards to its positioning between our location and the sun.
Venus
Venus is frequently the brightest object in the sky, emitting a bluish-green radiance. Even with a telescope, you can’t see the surface because the atmosphere is so thick.
- It is located nearer to the Sun than the Earth. Because it remains relatively close to the Sun and may be seen at dawn or night, Venus is known as the Morning Star or Evening Star.
- What you’ll need to see it: Nothing, not even black skies, is required to see Venus. Apart from the Sun and the Moon, Venus is one of the few things that can be seen before or after the Sun has set or risen.
The planet Venus derives its name from ancient Babylonians around 1600 BC associating it with the Goddess of love, and it is the only planet within our solar system named after a female figure.
The original cultures to witness this planet actually believed it was two separate objects; one seen around sunrise and another at sunset referred to as the Morning and Evening Stars.
Since Venus appearance wise is very similar to the Earth in size and shape it is often referred to as our sister planet, even though until this past decade very little was known about Venus or its surface. A thick layer of sulfuric clouds reside within Venus’s upper atmosphere that light cannot penetrate, making visibility and research from abroad near impossible.
It is thought to be the densest atmosphere of all the planets within our solar system, and therefore possibly the least likely place for humanity to colonize. It is also one of the brightest objects within the sky around sunrise and sunset each day, and countless reports across the world have mistaken Venus for a UFO or other rare celestial object.
Whether or not we can live on Venus is almost inconsequential to scientists though, because our solar twin still holds many answers that could possibly further explain the Earth’s future. Although the planet is currently very different from our own, research indicates that at its formation Venus had several striking similarities to our home.
Water was once abundantly present across the planet, and the planet’s core is believed to contain a crust and a mantle that is partially liquid just like our own. Venus’s current surface is made up of mountainous regions and valleys commonly found on rocky planets, but what was unexpected was the sheer number of flat, volcanic areas that have dominated the planet’s geographical makeup.
Venus’s thick atmosphere provides ample protection from meteors and asteroids, and experts believe that even giant planetary strikes are broken down into small enough pieces to avoid the serious scarring we see from impacts on other planets.
For every question that has been answered regarding Venus two more have been presented, making this planet a popular conversation piece among astronomers. Several future missions to study the planet in further detail have already been planned by the United States, Russia, and Japan.
What is actually known about Venus makes for an interesting astrological study. The planet completes a full orbit around the Sun every two hundred twenty-four days in almost a perfect circular pattern, which is approximately one third faster than the Earth’s trajectory.
It rotates once on its axis every two hundred forty-three days, which by practical terms means a day on Venus last longer than what we would define as a year. The planet also appears to be much younger than the Earth, and scientists predict its age to be around 1 billion years old.
Why this planet formed over three billion years after Earth may indeed be the greatest mystery in itself, and the answer may provide clues as to why it turned out so very different from our own planet.
Mars
Mars appears as a bright red dot in the sky, with white polar caps and dark surface patterns visible through a telescope.
- Where it is: The next planet out from Earth, and the closest one to us every 26 months.
- What you’ll need to see it: Mars’ orange-red tint makes it simple to spot with the naked eye, but it’s best seen using a small telescope.
The planet Mars has always been a fascinating subject of interest among those who did not closely follow astronomy, especially just before the turn of the 20th century when the idea of Martians inhabiting the nearby planet were possibly sending communications through space as a warning to Earth.
Giovanni Virginio Schiaparelli, an Italian astronomer who classified much of the glowing red planet during his studies in the late 1800’s named a dense network of structures on the planet “canali,” which literally translates to channels. A mistake in the translation led Americans to think he called them canals, which is essentially thought of as a man made structure.
Around the same time period, Austrian born inventor Nikola Tesla thought he picked up repetitive radio waves that could have possibly originated from the planet, and Mars Fever officially swept the nation. Although more modern technological studies have corrected these unfounded beliefs, scientists are still unsure of whether living organisms once inhabited Mars.
Recent studies show the building blocks for intelligent life were once in place on the planet, and although the core appears largely dormant many of those properties are still in place.
Scientists can say, however, with a fair amount of certainty that there is no life on Mars at the present time, because essentially the planet has become inactive and is considered dead. While there is significant evidence to show that liquid water, thought to be the catalyst of life, was once abundant across much of Mar’s surface, the lack of a proper atmosphere in its current state prevents significant accumulations from forming and remaining on the surface.
The tectonic plates found beneath the surface of Mars are no longer active; neither are any of the volcanos that scatter across its surface. The polar caps on the planet contain massive amounts of dry ice, and in 2007 NASA scientists determined if melted it would cover the entire planet in thirty-six feet of water.
The presence of sediments associated with water in recently explored regions of Mars could mean that there is still traces of flowing liquid on the planet’s surface, but further research would be required to either confirm or deny that theory.
In terms of size, Mars is about 1/6th the size of the Earth, meaning the surface area is nearly equivalent to Earth’s dry land. Much of the surface is covered with fine grains of iron oxide, commonly referred to as rust across our planet; silica-rich asalt is also present in large quantities.
Initial studies of the soil found traces of elements required in order for plants to grow but later findings have shown the presence of salt, which would inhibit such growth. While our rotational orbits around each planet’s respective axis is similar, Mars has a longer rotation around the Sun due to its relative distance.
Mars also possesses two separate moons, but both are thought instead to actually be asteroids. The term moon is applied in this case only because of a lack of a better term; since they both orbit Mars they qualify by definition.
The smaller of the two moons, Phobos, is slowly altering its orbit and expected to eventually collide with Mars or to break away from the gravitational pull completely, sending it on an unknown course across our solar system.
Both moons orbit dangerously close to the planet, their very existence and how they became associated with Mars is somewhat of a mystery to scientists. Mars is near an asteroid belt and has suffered thousands of direct hits throughout history, so the asteroid theory is currently the most popular explanation.
Jupiter
Jupiter is a long way from Earth, but due to its massive size, it shines brightly. You can see all of the planet’s larger moons in a line, and if you watch for several nights, you’ll notice how the moons move in relation to the planet. Jupiter’s cloud belts, which include patches and imperfections, give it a striped appearance; you can see them spin with Jupiter over the course of a night (Jupiter rotates once every 10 hours or so).
- Jupiter takes 12 years to complete one orbit around the Sun, therefore its position with regard to the stars will remain relatively constant over the course of a year. Simply look it up in a planet-finding chart to see where it is now.
- Jupiter’s cycle around the Sun takes 12 years to complete, so its position in relation to the stars will remain essentially stable over the course of a year. To figure out where it is presently, simply look it up in a planet-finding chart.
Jupiter has the distinction of being the largest planet within our solar system; it is so large that its size is two and a half times larger than every other planet in the solar system combined.
A disproportional overall mass leads scientists to believe that Jupiter could not contain any additional volume without actually shrinking in overall size, translating into theories that the massive planet has reached the absolute maximum diameter for its age and category.
Close inspection with even an amateur’s telescope shows that the planet actually bulges around the equator due to its mass and extreme magnetic properties. Some astronomers further contemplate that Jupiter may have actually been a failed star, but since the formation patterns of multiple star systems is largely unknown it is considered speculation at best.
This theory is further supported by the fact that Jupiter radiates more heat than what is absorbed by the sun, and scientific data shows that the planet was almost twice as large and much hotter in its early stages of formation.
Much about Jupiter is still a mystery though, due to the heavy ammonium cloud cover that surrounds the planet.
The cloud bands that encompass the planet rotate is alternating patterns parallel to different latitudes across the planet, and these formations vary both in size and in color from year to year.
The overall density of these cloud bands is believed to stretch over thirty-one miles towards the planet’s surface and is made up of two individual layers.
The inner clouds have been captured discharging lightning up to a thousand times ore powerful than what we experience on Earth; this is significant because the presence of water vapor in clouds is necessary for lighting to occur.
Other types of massive storm systems have also been viewed within these bands, the most popular of them being the Giant Red Spot. First discovered in 1831, this massive tornado like storm spins counter-clockwise twenty-two degrees south of Jupiter’s equator and has been in perpetual motion ever since (a separate claim suggests that the Giant Red Spot may have been around in 1665 but there is not enough data available to support or refute the statement).
The storm’s total mass is larger than Mercury, Venus, Earth, and Mars combined and it extends seven miles beyond the highest cloud barrier. It has encircled the entire planet several times at varying speeds, and very little is known what causes the storm to speed up or slow down.
Consequently, in 2000 three smaller storms that were encircling the planet merged into one and are now considered Red Spot Junior, although their overall mass is still much smaller than the original.
Another interesting and unique feature of Jupiter is its moons, all sixty-three of them. While the vast majority are only a few miles in diameter they still bear the classification for lack of an updated term There are also several within the larger moons that are both active and interesting areas of study.
Europa, for example, is believed to have liquid water beneath its surface that remains in constant motion as solid ice above it is drawn by Saturn’s magnetic pull. Some scientists even believe that Europa could support life since several key elements are present, but research techniques are still too primitive in order to tell for certain.
Because of the strong magnetosphere, which is estimated fourteen times stronger than Earth’s, these objects are believed to have been influenced and shaped by Jupiter’s presence, much like the formation of the solar system and many asteroid belts within it.
Saturn
Because of its rings, Saturn is a favorite among astronomers. The rings can be weak and near to edge-on at different times of the year, but they are usually brighter and more face-on. You won’t be able to see structures within the rings even with a huge telescope. Cloud belts blanket Saturn’s surface, but not as strongly as they do Jupiter’s.
- Saturn is further away from Jupiter than Jupiter and has a much longer orbital period (almost 30 years).
- What you’ll need to see it: Saturn is visible without a telescope, but you’ll need one to see its rings.
Saturn, a large gas giant and the sixth planet from the Sun, is mainly associated with the many rings that encompass the planet. It is the second largest planet within the solar system, smaller than only Jupiter, and shares many of the same physical properties.
Since this planet is so extremely far from the Sun, it completes one rotation every twenty-nine and a half years and makes a full rotation on its axis about every thirty days. Due to the enormous pressure placed on Saturn it is classified as an oblate spheroid, meaning it bulges around the equator and is flattened near the poles.
Very little was actually known about this planet when compared to others within our solar system; however, additional research within the past decade has shared several additional features of Saturn.
The rings that encompass Saturn may well be the most viewed celestial object within our solar system due to their natural beauty and questionable origins.
Many scientists speculate that the ring formations were formed due to a collision between Saturn and one of its moons, while others hypothesize that they are leftover material from the planet’s creation. The rings are mainly composed of water ice with traces of amorphous carbon, and they extend upwards of seventy five thousand miles from Saturn’s equator.
The size of the debris within this planet’s rings vary from tiny dust particles to the relative size of a modern vehicle.
The planet itself is believed to be a rocky surface surrounded by gases of hydrogen and helium, much like Jupiter is. The extremely hot core of Saturn reaches temperatures of over twenty-one thousand degrees Fahrenheit, and the planet expels two and a half times more energy than it absorbs from the Sun.
Outside the core is speculated to be liquid hydrogen, and it must undergo some type of secondary reaction in order to produce such extreme temperatures. Although this process is not completely understood by scientists it could possibly be explained by helium rising up from the center of the planet and causing friction as it passes the lighter hydrogen gasses.
Another extraordinary study of the planet Saturn is its many moons that orbit around the planet. Sixty-one are known to exist in all, although over three quarters of them are less than 50 km in diameter. Each of them are named after a Greek Titan, with the name Titan reserved for the largest natural satellite.
Saturn’s second largest moon, Rhea, is believed to have its own ring system which was previously unheard of. Since the three rings are located near the equator, meteorite impacts could in fact explain their existence.
Saturn’s largest moon, Titan, and it is an especially interesting area of study due to its similarities to the Earth. It is the only known natural satellite of its kind with a dense atmosphere, comprised of over 98% nitrogen.
An additional unique feature is the presence of hydrocarbon lakes covering Titan’s poles, this is not present anywhere else within our solar system except on Earth. Less than one percent of the Sun’s rays penetrate the atmosphere, making it around negative two hundred ninety degrees Fahrenheit.
The moon also produces high quantities of Methane gas, which burns up in the atmosphere but is regenerated near the polar caps. Due to Titan’s gravity human visitors would be able to fly across its surface, although that may not be a realistic goal to expect within our lifetimes.
Uranus
Uranus is a faint planet with cloudlike bands like Jupiter and Saturn. However, big, professional telescopes are usually required to see these belts.
- It is located at a great distance from the Sun (19 times farther than the Earth).
- To see Uranus, you’ll need binoculars to locate it amid the stars and a professional telescope to peer into its atmosphere. Its pale, greenish sphere can be seen with a small telescope.
Uranus is the second furthest planet from the Sun and is the third largest within our solar system at fourteen and a half times larger than the Earth. As with the other gas giants it shares its distinction with, the planet’s surface is made up of rock and ice with large traces of helium and hydrogen present.
With surface temperatures reaching negative three hundred seventy-one degrees Fahrenheit, Uranus is by far the coldest planet within our solar system. Uranus can be spotted with the naked eye within darkened skies, but its glow is much fainter than other recognizable planets.
The surface is covered in a thick cloud structure saturated with water at lower levels and methane within the uppermost layer. High winds are also experienced on the planet, which are thought to reach speeds in excess of five hundred and sixty miles per hour.
A unique feature of Uranus is the configuration of its axis, which is almost completely sideways and typically where the equator would be on other planets. Like Saturn, Uranus does have several rings that orbit around the equator; but due to its unique positioning they instead appear above and below the target, much like the appearance of a tire on a wheel.
There are thirteen total rings in all, and from what astronomers can tell they did not form with Uranus because of their relatively low density. A collision with the planet and one of the moons is one of the most likely scenarios for their formation.
Despite Uranus’s large size, its density is higher than only Saturn’s. This tells scientists that a rocky core is likely, with ice contained within the mantle and an outer region made up of gaseous forms of hydrogen and helium. Because a large portion of its interior is composed of ice or various liquids, both Neptune and Uranus are often referred to as ice giants instead of gas giants like Saturn and Jupiter.
There are those within the scientific community, however, that do not agree with these assumptions and feel the separate naming classifications are premature since other theories have been presented that could possibly account for the low density.
Another interesting feature of Uranus is its 27 moons with names contrived from characters within the works of Shakespeare and Alexander Pope, The five main satellites are Miranda, Ariel, Umbriel, Titania, and Oberon; and each of them are expected to be as much as fifty percent ice combined with rock.
From what little evidence there is available about this region within our solar system, it appears that each of these natural satellites were formed at different times. Ariel, for example, has a very smooth surface with very few craters while Umbriel and Oberon are covered with multiple large impact zones.
As previously mentioned, much of how Uranus formed and its current makeup is still completely unknown due to a lack of concrete data. The only time Uranus has been visited was by NASA’s Voyager Two spacecraft in January of 1986.
Although much of the planet, its rings, the atmosphere, and the five largest moons were partially mapped during that fly-by there is still much to be discovered. There is currently no return mission scheduled, so it is unknown when more information may become available to explain several of Uranus’s more perplexing features.
Neptune
Except through the greatest professional telescopes, Neptune appears exceedingly pale and featureless.
- It is located at a great distance from the Sun (30 times farther than the Earth).
- What you’ll need to see it: To see Neptune at all, you’ll need a tiny telescope. It appears as a faint, bluish dot through a small telescope.
Neptune is the furthest planet from our Sun and named after the Roman God of the sea. As far as planetary bodies are concerned it is the fourth largest planet in diameter and the third largest in mass. An interesting notation is that Neptune was the first planet ever discovered by mathematical calculation derived by French astronomer Alexis Bouvard.
From visual studies he determined that there was an interruption in Uranus’s orbit that could only be caused by a gravitational field large enough to be from a separate planet, and by deducting the relative interruption in orbit he hypothesized where an additional planet should have been located within our solar system. As director of the Paris Observatory, Bouvard vigilantly searched for the spherical object he insisted was there but he was never able to substantiate this theory.
The discovery of Neptune and its largest moon Triton was not made until after his death, but since it was located due to his mathematical research fellow scientists John Couch Adams and Urbain Le Verrier granted him the formal credit for the discovery.
Composition wise, Neptune is very similar to Uranus in that it is comprised of mostly ices formed from ammonia, methane, and water.
The methane present within its outmost regions grants the planet its blue coloration when seen from afar, and like Uranus it has extremely cold surface temperatures reaching negative three hundred degrees Fahrenheit.
Since Neptune is one and a half times further from the Sun and receives only forty percent as much sunlight, it is known that the planet must exert some form of internal heat to make up for the difference.
Neptune has been found to generate almost two and a half times more energy than it absorbs from sunlight, which in itself is quite a mystery that scientists can not fully explain.
Neptune also possesses some of the most extreme weather found anywhere within the solar system, which is a bit puzzling to scientists that the furthest planet from the Sun would expel among the highest levels of energy.
In 1989 scientists discovered an anti cyclonic storm system in the Southern Hemisphere that had close similarities to the Great Red Spot of Jupiter; then in 1994 the planet was viewed with the assistance of the Hubble Telescope and a similar storm movement was spotted within the Northern Hemisphere.
Surface winds have been verified blowing as strong as thirteen hundred miles per hour, which is by far the strongest found anywhere within our solar system.
Neptune is never visible to the naked eye due to the extreme distance from Earth and its relatively low brightness measuring between 7.7 and 8.0, but through moderately powered telescopes partial ring formations and several moons have been discovered.
The largest moon, Triton, is completely unique from previous discoveries because it rotates against Neptune’s orbit. Because of its unnatural rotation around Neptune it could not have formed within the region, and scientists hypothesize that it was actually a dwarf planet originating from the nearby Kuiper belt.
Measured in 1989, Triton was considered the coldest object within the solar system; and because of its unnatural rotation it will eventually be destroyed by Neptune’s gravitational pull and tidal surges.
Pluto
Pluto appears to be nothing more than a brilliant dot, even when viewed via the Hubble Space Telescope. Pluto was “demoted” from full planet status by the International Astronomical Union in 2006; it is now officially classified as a dwarf planet, however astronomers continue to question its classification.
- It is located at the farthest point from the Sun.
- What you’ll need to see it: Only a strong, professional telescope will be able to glimpse Pluto.
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