Neptune is the eighth planet from the Sun and the farthest major planet in the solar system. Neptune is characterized by its deep blue hue, a dynamic atmosphere with fierce storms, extreme cold, and a system of rings and moons. Neptune is an ice giant with powerful winds, and its magnetic field, which is offset from its center. The planet exerts gravitational influence on objects in the Kuiper Belt and serves as a key subject in the study of planetary formation and dynamics. Learn about Neptune’s discovery, physical properties, and role in shaping our understanding of distant celestial bodies.

Johann Gottfried Galle discovered Neptune at the Berlin Observatory on September 23, 1846. Urbain Le Verrier and John Couch Adams had calculated Neptune’s existence and location. 

Neptune orbits 30 times farther from the Sun than Earth. Neptune takes 165 Earth years to complete one orbit around the Sun. Neptune experiences supersonic winds up to 2,100 km/h (1,305 mph). Neptune’s magnetic field is tilted at 46.8° from its rotation axis. Neptune’s surface gravity is similar to Earth’s.

Neptune’s color is a greenish-blue with a hint of blue. Neptune appears bluer than Uranus due to its thinner haze layer. Neptune’s thinner atmospheric haze layer allows more blue light to be visible. Methane in Neptune’s atmosphere absorbs red light and reflects blue light.

Neptune’s volume is 57.7 times Earth’s volume. Neptune’s equatorial diameter extends to 49,528 km (30,775 miles) at the one-bar pressure level.

Triton is the largest moon of Neptune, discovered by William Lassell in 1846. Neptune’s moons are named after characters from Greek or Roman mythology associated with Poseidon or Neptune.

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Neptune is the eighth planet from the Sun in our solar system, an ice giant known for its color, winds, and position as the outermost of the known planets. Neptune has a diameter of 49,244 kilometers (30,598 miles), making it the fourth-largest planet in the solar system. Neptune’s mass is 17 times that of Earth, ranking it as the third-most-massive planet. Neptune orbits the Sun at a distance of 4.5 billion kilometers, completing one orbit every 164.79 years. Neptune experiences weather conditions with winds reaching speeds over 2,000 kilometers per hour (over 1,243 miles per hour). Neptune’s distinct blue color results from methane in its atmosphere absorbing red light and reflecting blue light.

Neptune is classified as an ice giant due to its composition. Neptune consists of ices including water, ammonia, and methane, along with a rocky core. The planet’s core is made of iron, nickel, and silicates, with a mass 1.2 times that of Earth. Neptune’s mantle contains water, ammonia, and methane ices, while its atmosphere is hydrogen, helium, and methane gas.

Neptune has a diameter of 49,528 kilometers (30,598 miles), making it about 3.9 times larger than Earth. Neptune experiences extreme temperatures with cloud tops reaching -218°C (-330°F). Neptune lacks a solid surface, transitioning from an atmosphere to liquid hydrogen and helium layers under pressure.

The planet has 16 known moons, with Triton being the largest. Triton contains 99.7% of the mass of Neptune’s satellite system and has a unique retrograde orbit.  Neptune has rings which are composed of dust, rock, ice particles, and debris.

Urbain Le Verrier predicted Neptune’s position in 1846. Johann Galle observed Neptune through a telescope on September 23, 1846, confirming Le Verrier’s calculations. This discovery marked a milestone in astronomy, demonstrating the power of mathematical predictions in identifying new celestial bodies.

Neptune is not a gas giant. Neptune is classified as an ice giant due to its composition of heavier elements like water, methane, and ammonia. Gas giants like Jupiter and Saturn consist of hydrogen and helium, while Neptune has a mantle of compressed ices.

The solar system contains two ice giants (Neptune and Uranus) and two gas giants (Jupiter and Saturn). Ice giants have a small rocky core surrounded by a fluid of icy materials. Gas giants possess liquid metallic hydrogen interiors. Neptune’s structure includes layers of rock, water, methane, and ammonia. The formation of the solar system resulted in the formation of two inner rocky planets, two ice giants, and two gas giants.

Ice giants like Neptune and Uranus contain proportions of water, methane, and ammonia. Gas giants like Jupiter and Saturn consist of hydrogen and helium. Neptune’s mass is 17 times that of Earth. Ju

Neptune’s atmosphere consists of hydrogen, helium, and methane.  The methane absorbs red light and reflects blue light, giving the planet its distinctive blue color. Neptune has the strongest winds in the solar system, reaching speeds of 1,200 mph (1,931 km/h).

Neptune is 4.6 billion years old. The planet formed from a cloud of gas and dust along with the rest of the solar system. Neptune underwent migration to its current position after formation.

Estimates place Neptune’s age at 4.5 to 4.6 billion years since its formation. Astronomers agree on this age range, aligning with the formation of the entire solar system. Neptune has existed for only a fraction of human history in comparison to its lifespan. Humans have known about Neptune for 165 Earth years since its discovery in 1846. This timespan represents one Neptunian year, as Neptune takes 165 Earth years to complete a single orbit around the Sun.

Neptune was discovered by Johann Gottfried Galle at the Berlin Observatory on September 23, 1846, based on calculations by Urbain Le Verrier and John Couch Adams. Le Verrier and Adams predicted Neptune’s existence and location through mathematical calculations. Le Verrier sent his calculations to Galle, enabling the planet’s observation. Galle found Neptune within 1° of Le Verrier’s predicted position. Neptune became a planet discovered through mathematical predictions rather than direct observations. Neptune’s discovery provided evidence for Newton’s theories of gravitation and laws of motion.

The mathematical predictions leading to Neptune’s discovery began with Urbain Le Verrier in June 1845. Le Verrier used Newton’s law of gravitation to calculate the mass, position, and orbit of a planet causing discrepancies in Uranus’s orbit. John Couch Adams started similar calculations in 1841, completing them by September-October 1845. Adams’ predictions were inaccurate, being 12° off from Neptune’s actual position. Le Verrier’s calculations were precise, placing Neptune within 1° of its true location.

Johann Gottfried Galle received Le Verrier’s calculations on September 23, 1846. Galle and his student Heinrich Louis d’Arrest began searching for the predicted planet using the Berlin Observatory’s telescope. They observed Neptune on the night of September 23-24, 1846, confirming its existence and location. William Lassell discovered Neptune’s moon Triton 17 days after Neptune’s initial observation. The discovery of Neptune marked a collaboration between theoretical mathematicians and observational astronomers, ushering in an era of planetary science.

Neptune got its name from the Roman god of the sea. Astronomers suggested the name in 1846, following the tradition of naming planets after Roman gods. Le Verrier proposed “Neptune”, which became accepted by year’s end due to the planet’s color and stormy atmosphere.

Urbain Le Verrier and John Couch Adams made mathematical predictions of Neptune’s existence through orbital calculations. Johann Galle and Heinrich d’Arrest made the discovery of Neptune in 1846 based on Le Verrier’s calculations. Neptune’s connection to Roman mythology is rooted in its namesake. Neptune was the Roman god of the sea, freshwater bodies, and horses, equivalent to the Greek god Poseidon. Neptune was depicted carrying a trident, symbolizing his dominion over the seas.

The rationale for choosing the name Neptune aligned with the tradition of naming planets after Roman deities. Neptune’s color and atmosphere resembled the ocean, fitting its association with the sea god. Le Verrier proposed the name Neptune, which gained acceptance due to its relevance to the planet’s characteristics. Other names suggested for the planet included Janus by Johann Galle and Oceanus by James Challis. Neptune’s naming reflected influences and data, continuing the mythological naming convention established for planets like Uranus.

Facts about Neptune include that the planet orbits 30 times farther from the sun than Earth. Neptune is an ice giant with greater mass than Uranus. Neptune’s atmosphere contains methane, causing its blue color. Neptune experiences supersonic winds up to 600 meters per second (1,968.5 feet per second).

Some interesting facts about Neptune are listed below.

Neptune orbits 30 times farther from the Sun than Earth and takes 165 Earth years to complete one orbit.

Neptune’s atmosphere contains methane, causing its distinct blue color.

Neptune experiences supersonic winds up to 2,100 km/h (1,305 mph).

Neptune’s atmosphere is composed of hydrogen, helium, and methane.

Methane in Neptune’s atmosphere absorbs red light, contributing to its blue hue.

Voyager 2 spacecraft observed Neptune’s storm system, the Great Dark Spot, in 1989.

Neptune’s magnetic field is tilted at 46.8° from its rotation axis and offset by 0.55 of Neptune’s radius from the planet’s center.

Neptune orbits at the boundary of the main planetary system.

Neptune has 16 known moons, with Triton being the largest and exhibiting geysers that eject ice particles into space.

Triton, Neptune’s largest moon, orbits in a retrograde direction and shows geological activity.

Nereid, Neptune’s third-largest moon, has an irregular and eccentric orbit.

Neptune’s ring system consists of six rings, with one containing arcs.

Voyager 2 provided information about Neptune during its 1989 flyby.

Neptune’s surface gravity is similar to Earth’s, despite its ice giant status.

A day on Neptune lasts 16 hours.

Neptune’s average atmospheric temperature is 73 Kelvin (-200°C).

The color of Neptune is greenish-blue with a hint of blue. Neptune shares a similar shade to Uranus, but appears bluer due to its thinner haze layer. Images amplified Neptune’s color, making it seem bluer than it is.

Studies reveal Neptune’s hue to be pale greenish-blue, contrasting with earlier perceptions. Voyager 2 spacecraft captured images of Neptune in the late 1980s, depicting the planet as bright blue. These observations were later improved, resulting in images showing Neptune as a rich blue color. The upgraded images were composites built from single-color observations, saturating Neptune’s appearance.

Neptune appears bluer than Uranus at visible wavelengths. Neptune’s thinner atmospheric haze layer allows more blue light to be visible, contributing to its bluer appearance. Professor Patrick Irwin from the University of Oxford led studies on Neptune’s color. His team reprocessed Voyager 2 data and incorporated information from the Hubble Space Telescope and the European Southern Observatory’s Large Telescope. The findings suggest Neptune’s color is characterized as greenish-blue with a hint of blue.

Neptune’s diameter is 49,244 kilometers (30,598 miles). Neptune’s diameter is four times Earth’s size. Neptune’s volume is 57.7 times Earth’s volume, with fifty-seven Earths fitting inside Neptune.

Neptune’s diameter measures 49,244 km (30,598.8 miles). The equatorial diameter of Neptune extends to 49,528 km (30,775 miles) at the one-bar pressure level. Neptune’s diameter is approximated as 49,500 km (30,850 miles) for simplicity purposes. Neptune’s equatorial diameter is larger than its average diameter due to the planet’s equatorial bulge. Neptune’s oblate spheroid shape results from its rapid rotation. Neptune’s size characterizes it as the smallest of the gas planets in our solar system. Neptune’s diameter dwarfs the terrestrial planets like Earth, reflecting its size in the context of the solar system.

The mass of Neptune is 1.02409 × 10^24 kg (2.26 × 10^24 lbs). Neptune’s mass is 17.15 times Earth’s mass and consists of hydrogen, helium, and ices. Scientists calculate Neptune’s mass based on gravitational interactions and orbital dynamics of nearby celestial bodies.

Neptune’s mass is expressed as 1.024 × 10^26 kg (2.26 × 10^25 lbs) in literature. This value represents the accepted and precise measurement of Neptune’s mass. Some sources provide a precise figure of 1.0243 × 10^26 kg (2.26 × 10^25 lbs). Researchers round Neptune’s mass to 1.02 × 10^26 kg (2.25 × 10^26 lbs) for simplicity in certain contexts.

The value 102.409 × 10^24 kg (225.4 × 10^24 lbs) is mathematically equivalent to 1.02409 × 10^26 kg (2.26 × 10^26 lbs), though is used less in scientific publications. Neptune’s mass converted to metric tons equals 1.02 × 10^23 metric tons. Scientists prefer to use kilograms for planetary masses in most scientific discussions and publications.

Neptune has 16 known moons. Triton, discovered by William Lassell in 1846, is the largest. Voyager’s 1989 flyby revealed Despina, Thalassa, and Larissa.

Neptune has 16 confirmed moons. Two moons were discovered before the Voyager 2 flyby: Triton and Nereid. Triton stands out as the largest moon of Neptune, discovered by William Lassell in 1846, 17 days after Neptune’s discovery. Triton is the seventh-largest moon in the solar system and the only large moon orbiting Neptune. Triton exhibits characteristics, including a retrograde orbit opposite to Neptune’s rotation and geological activity with nitrogen gas geysers.

Nereid, discovered in 1949, is the second-largest moon of Neptune. Voyager 2’s 1989 flyby revealed six moons. Observations by telescopes and the Hubble Space Telescope led to the discovery of more moons in 2002 and 2003.  Some moons, like Psamathe and Neso, have eccentric and distant orbits around Neptune.

Neptune has rings around it. Neptune’s ring system consists of five rings: Galle, Leverrier, Lassell, Arago, and Adams. The rings were discovered through stellar occultation observations on July 22, 1984, and confirmed by NASA’s Voyager 2 spacecraft in 1989.

Neptune’s rings are composed of dust, ice particles, and debris. The ring particles range in size from microns to meters, with water ice, silicates, and carbon-based compounds making up the majority of the material. Neptune’s rings are thin and faint compared to gas giants’ ring systems. The rings have low albedos (less than 0.07), explaining their faint appearance.

Ring arcs are a feature of Neptune’s ring system. These discontinuous segments are distributed within a 45° segment of the Adams ring. The ring arcs range in length from about 1,000 km (621 miles) to more than 10,000 km (6,213 miles), with five arcs named Courage, Liberté, Egalité 1, Egalité 2, and Fraternité. Neptune’s ring arcs are regions with high particle density, setting them apart from the rings of gas giants.

Voyager 2 provided confirmation of Neptune’s ring system in 1989. The spacecraft transmitted the first detailed images of Neptune’s rings on August 26, 1989, revealing two main rings and additional faint rings. Voyager 2 took images at phase angles to understand particle-size distribution and forward-scattering behavior. The spacecraft’s observations showed Neptune’s rings are narrow, clumpy, and dusty, with a forward-scattering behavior that makes them appear brighter at certain viewing angles.

The stability of Neptune’s ring arcs is influenced by the gravitational interactions with the planet’s moons. Galatea, one of Neptune’s moons discovered by Voyager 2, acts as a shepherd moon for the Adams ring. Scientists have observed that Neptune’s ring arcs remain stable over at least five years. Resonant interaction between the Adams ring and Galatea is believed to maintain the arcs’ structure and stability. Research continues to explore theories on the longevity of Neptune’s ring structure.

The distance of Neptune from Earth varies due to orbits. Neptune and Earth are 4.3 billion kilometers apart at closest approach and 4.7 billion kilometers at farthest separation. The average distance is 4.5 billion kilometers or 30.65 Astronomical Units.

Neptune’s distance from Earth fluctuates due to the elliptical orbits of both planets. Neptune approaches Earth at its closest distance of 2.7 billion miles (4.3 billion kilometers). Neptune reaches its farthest point from Earth at 2.9 billion miles (4.7 billion kilometers). The average distance between Neptune and Earth is 2.8 billion miles (4.5 billion kilometers), which is 30 astronomical units.

Current measurements place Neptune at a distance of 4,593,533,752 kilometers (2.85 billion miles) from Earth. This distance equals 30.705877 astronomical units. Neptune’s orbit around the Sun varies in distance.

Neptune’s distance poses difficulties for research and study. Light takes 4 hours and 15 minutes to travel from Neptune to Earth at their separation. Neptune remains the most distant planet in our solar system, making it one of the most difficult celestial objects to investigate from Earth.

Neptune compares to Earth as a giant planet with a diameter four times wider. Neptune’s mass is 17 times Earth’s, and its volume contains 57 Earths. Neptune has higher density than gas giants but lower density than Earth.

The comparison between Neptune and Earth is detailed in the table below.

Neptune is an ice giant composed of water, methane, and ammonia. Earth is a terrestrial planet with a solid rocky surface and landforms. Neptune’s diameter is 3.9 times that of Earth, measuring 49,528 kilometers (30,598 miles) compared to Earth’s 12,742 kilometers (7,918 miles). Earth’s atmosphere contains nitrogen and oxygen, resulting in surface colors due to land and water features. Neptune’s surface clouds have cold temperatures around -201 degrees Celsius. Earth’s surface temperature is 15 degrees Celsius, ranging from -89 to 57 degrees Celsius.

Neptune orbits the Sun at a distance of 2.8 billion miles, 30 times farther than Earth. Earth is positioned in the habitable zone of our solar system. Neptune’s surface gravity is 14% stronger than Earth’s, causing a 100 lb (45.36 kg) person on Earth to weigh 110-114 lbs (49.90-51.71 kg) on Neptune. Earth has one moon. Triton orbits Neptune in a retrograde direction, unlike Earth’s moon which orbits in a prograde direction. Neptune’s year lasts 164.79 Earth years, while Earth completes one orbit around the Sun in 365.25 days.

Neptune’s orbital period is 164.79 years. Neptune makes an orbit around the Sun in 60,182 Earth days. In Neptunian time, a year lasts 165 Earth years or 60,190 Earth days.

Neptune’s sidereal period, the time it takes to complete one full orbit around the Sun relative to the fixed stars, is 164.8 Earth years. This duration translates to 60,195 Earth days, highlighting the distance Neptune travels in its orbit. Neptune’s year encompasses 89,666 Neptunian solar days, demonstrating the difference between its rotational and orbital periods.

Neptune has a synodic period of 367.49 Earth days. The synodic period represents the time it takes for Neptune to return to the same position in the sky relative to Earth and the Sun. Neptune’s synodic period is critical for observing its retrograde motion from Earth’s perspective. Neptune orbits at a speed of 5.43 km/s (3.37 mi/s) along its path, slower than the inner planets due to its distance from the Sun.

A day on Neptune is 16 hours long. Neptune takes 16 hours to complete one rotation, defining a Neptunian day. Neptune’s rotation contributes to its strong winds and atmospheric dynamics, despite its larger size and distance from the Sun compared to Earth.

One range estimate puts Neptune’s day at 15.8 hours. Some calculations suggest a day on Neptune lasts 15 hours. An estimate proposes a day length of 15.97 hours. The precise measurement indicates Neptune’s day spans 16.11 hours. The range estimate extends to 16.6 hours. Neptune’s status as a gas giant contributes to the challenge of obtaining measurements. Parts of Neptune rotate at varying speeds due to its gaseous composition. Scientists have refined their measurements over time using technologies like the Hubble Space Telescope. The sidereal rotation period of Neptune is recorded as 16 hours, 6 minutes, and 36 seconds. Erich Karkoschka’s research estimated Neptune’s day to be 15 hours, 57 minutes, and 59 seconds. These variations in estimates highlight the ongoing scientific efforts to determine Neptune’s rotational period.

Neptune is made of a hydrogen-helium atmosphere, a hot dense fluid mantle containing water, methane, and ammonia, and a small rocky core. Neptune’s composition classifies it as one of two ice giants in the outer solar system.

Neptune’s atmosphere consists of hydrogen and helium gases. Hydrogen gas accounts for 80% of the atmospheric volume, serving as the main constituent. Helium gas makes up 19% of the atmosphere, acting as an inert secondary constituent. Methane gas comprises about 2.3% of the atmospheric volume. Methane influences the color of the planet, absorbing red light and reflecting blue, giving Neptune its distinctive blue appearance.

Neptune’s mantle is composed of a hot, dense fluid rich in water, methane, and ammonia. Water ice is a compound in the mantle structure, existing in a melted state due to high temperatures and pressures. Methane ice accounts for up to 10% of Neptune’s mass, contributing to the planet’s composition. Ammonia ice is another mantle compound, present alongside water and methane. Hydrogen sulfide is a compound found in Neptune’s mantle, contributing to the planet’s coloration.

Neptune’s core is solid and composed of heavy elements. The core contains iron, nickel, and silicates in a rocky state. Neptune’s core has 1.2 times the mass of Earth, experiencing pressure estimated at 7 Mbar or 700 GPa at its center. The solid core is surrounded by the mantle of melted ices, creating a layered internal structure that distinguishes Neptune as an ice giant.

Neptune’s atmosphere is made of hydrogen and helium with a little bit of methane. Methane absorbs red light, giving Neptune its distinct blue color. The atmosphere contains trace amounts of gases and extends to great depths, forming 5-10% of the planet’s mass.

Neptune’s atmosphere composition consists of hydrogen and helium. Hydrogen abundance is 80%, while helium abundance is 19%. Methane constitutes 2.3% of Neptune’s atmosphere by volume. Methane in Neptune’s atmosphere absorbs red light and reflects blue light, resulting in the planet’s characteristic blue color. Neptune’s atmosphere appears bluer compared to Uranus’s atmosphere due to higher methane content.

Neptune’s atmosphere structure includes layers with temperature and pressure profiles. Cloud formation involves chemicals including ammonia, methane, and hydrogen sulfide. Methane clouds form at pressures below one bar. Ammonia and hydrogen sulfide clouds form at pressures between 1-5 bars. Water-ice clouds form at pressures around 50 bars. Neptune’s atmosphere temperature varies with altitude. Cloud tops have a temperature around -346°F (-210°C). Temperature in the troposphere decreases with increasing altitude, while temperature in the stratosphere increases with altitude. Neptune’s atmosphere pressure in the lower troposphere ranges from one to five bars. Pressure in deeper atmospheric layers reaches 10 GPa. Neptune’s atmosphere temperature near the core reaches 7,000 K (12,000 °F, 6,700 °C).

Neptune has water in different forms. Neptune’s mantle contains water, ammonia, and methane as “icy materials” – fluids. Neptune’s atmosphere has water clouds. Neptune’s interior has a water ocean 8,000 km thick (4,971 miles thick). Neptune is classified as an “ice giant” with water ice.

Neptune’s mantle contains an estimated 10 to 15 Earth masses of water, ammonia, and methane. Neptune’s core is composed of iron, nickel, and silicates, with a mass 1.2 times that of Earth. Studies propose the existence of a distinct layer of water beneath Neptune’s atmosphere. This layer forms a liquid water ocean, contributing to Neptune’s classification as an ice giant.

Neptune’s atmosphere contains water vapor, but not in sufficient quantities to form water droplets. The planet’s atmospheric composition includes cloud layers formed from ammonia, hydrogen sulfide, and water ice. Neptune’s atmosphere extends 5 to 10% of the way towards the core, transitioning into a mantle composed of hot, dense fluid. The atmospheric water vapor reaches equilibrium with the interior water content, maintaining a balance throughout the planet’s structure.

Neptune lacks a solid surface, with its water existing as a supercritical fluid or superionic state due to extreme conditions. The planet’s moon, Triton, features substantial amounts of water ice on its surface. Triton’s surface is one of the coldest in the solar system and shows evidence of cryovolcanism and geologic activity. Triton is believed to have a subsurface ocean composed of water ice, contributing to Neptune’s water content.

Water on Neptune exists in various states throughout the planet’s structure. In the interior, water forms a supercritical fluid or superionic water at depths. Under pressure, ice formations occur within Neptune’s layers. The planet’s composition includes water in vapor form in the atmosphere and liquid states in different layers. Neptune’s mantle contains a water-ammonia ocean, forming a supercritical fluid that is conductive.

The climate on Neptune is cold, with an average surface temperature of -328°F (-200°C). Neptune experiences the solar system’s fastest winds, reaching 2,100 km/h (1,304 mph). Huge storms, dark spots, and dynamic cloud patterns characterize Neptune’s weather.

The cloud tops in Neptune’s atmosphere average around 51.8 K (-221.3°C), while the temperature rises to 72 K (-201.15°C) at 1 bar pressure. Atmospheric pressure increases with depth, reaching 10 GPa (10^5 atmospheres) in deeper layers. The core temperature is estimated at 7,000 K (6,700°C), creating a temperature gradient throughout the planet.

Neptune’s atmosphere consists of hydrogen (80%) and helium (19%), with trace amounts of methane. Methane is responsible for Neptune’s blue color by absorbing red light. Lower atmospheric regions contain increasing concentrations of methane, ammonia, and water. The stratosphere includes trace amounts of carbon monoxide, hydrogen cyanide, ethane, and ethyne, produced by ultraviolet photolysis of methane.

Neptune experiences the fastest winds in the solar system, reaching velocities up to 2,100 km/h (1,300 mph). Wind speeds range from 20 m/s ( 44.7 mph) easterly to 325 m/s ( 727.6 mph) westward. Winds at cloud tops vary from 400 m/s (1,312 ft/s) along the equator to 250 m/s (820 ft/s) at the poles. Neptune’s winds move opposite to the planet’s rotation, with prograde rotation at high latitudes and retrograde rotation at lower latitudes.

Storm systems on Neptune are intense and dynamic. The Dark Spot, similar to Jupiter’s Red Spot, exemplifies the planet’s storm activity. Neptune’s storms are less frequent than Jupiter’s but more active than those on Uranus due to higher internal heating. Storm duration varies, with some persisting for years with others dissipating quickly.

Neptune’s clouds vary in composition and altitude. Lower level clouds consist of methane and exist at pressures below one bar. Clouds between one and five bars are composed of ammonia and hydrogen sulfide. Higher clouds contain ammonia, ammonium sulfide, hydrogen sulfide, and water, with water ice clouds present at pressures around 50 bars. Higher altitude clouds, found 50-110 km (31-68 miles) above the cloud deck, cast shadows on the cloud layers below.

Neptune has seasons like Earth, experiencing spring, summer, fall, and winter. Neptune’s axial tilt causes hemispheres to receive varying sunlight, resulting in seasonal transitions. Each season lasts over 40 years due to Neptune’s long orbit around the Sun.

Neptune’s orbital period is 164.79 Earth years. A “Neptune year” encompasses all four seasons. Neptune orbits the Sun at a distance of 30.1 astronomical units (AU). The planet’s orbit is circular with an eccentricity of 0.008678, second only to Venus in the solar system. Neptune’s distance from the Sun varies, ranging from 29.81 AU at perihelion to 30.33 AU at aphelion.

Neptune’s axial tilt of 28.32 degrees influences its seasonal variations. The planet’s rotation period is 16.11 hours, constituting a “Neptune day”. Neptune’s atmosphere undergoes differential rotation, with the equatorial zone rotating in 18 hours and polar regions in 12 hours. The combination of axial tilt and rotation creates pronounced seasonal effects on the planet.

Solar energy at Neptune’s distance is weaker than on Earth. Sunlight on Neptune is 900 times less bright than on Earth. Noon on Neptune appears as twilight to Earth observers. Neptune’s average temperature is around -200°C (around -328°F), with differences between poles and equator. The south pole is 10°C (50°F) warmer than the rest of the planet during its summer. Each of Neptune’s seasons lasts for over 40 Earth years due to its long orbital period. Neptune’s hemisphere experiences a 40-year summer, during which cloud bands become wider and brighter due to increased solar heating.

Neptune’s temperature range extends from -360°F (-218°C) at cloud tops to 9,300°F (5,100°C) in the core. Surface temperature, defined as Earth’s sea-level pressure equivalent, is -346°F (-201°C). The planet’s average temperature is -353°F (-214°C).

Neptune’s temperatures vary from its layers to its “surface”. The minimum temperature in Neptune’s atmosphere reaches 50 K (-370°F, -223°C) in the upper regions. Average temperatures in Neptune’s atmosphere range from -364°F (-220°C) to -353°F (-214°C). Neptune’s “surface” temperature, defined at Earth’s sea-level pressure equivalent, is -346°F (-201°C).

Neptune’s internal temperatures are different from its atmospheric conditions. The core of Neptune reaches 7273 K (12,632°F, 7,000°C), rivaling the surface temperature of the Sun. Neptune’s center temperature is estimated to be around 5400 K (9,300°F, 5,100°C). These extreme internal temperatures are a result of Neptune’s composition and internal heating mechanisms as an ice giant in our solar system.

The gravity on Neptune is 11.15 meters per second squared (m/s^2) (36.5 feet per second squared). Neptune’s surface gravity is 1.14 times stronger than Earth’s. A person weighing 100 pounds (45.36 kg) on Earth weighs 114 pounds (51.71 kg) on Neptune.

Neptune’s surface gravity is measured at 11.15 m/s² (36.5 ft/s²) at the 1 bar pressure level. The gravity at this pressure level is higher at 11.27 m/s² (36.96 ft/s²). Neptune’s surface gravity can be expressed as 1,115 cm/s² (438.5 in/s²), providing a unit of measurement for the same gravitational force.

Neptune’s gravity is stronger than Earth’s gravity. The ratio of Neptune’s gravity to Earth’s gravity is 1.15, meaning objects on Neptune experience 15% more gravitational pull. Neptune’s gravity is described as 1.14 g (11.2 m/s²) to Earth’s gravity or 1.1 times Earth’s gravity (10.8 m/s²). In percentage terms, Neptune’s gravitational force is 119% of Earth’s gravitational force.

How much you weigh on Neptune depends on your Earth weight. A 70 kg (154.3 lbs) person on Earth weighs 79.8 kg (175.5 lbs) on Neptune. Neptune’s gravity is 1.14 times Earth’s gravity, causing objects to weigh more.

To calculate your weight on Neptune, multiply your Earth weight by 1.12. A person weighing 100 lbs (45.36 kg) on Earth weighs 110 lbs (49.90 kg) on Neptune, representing 110% of their Earth weight. Someone weighing 150 lbs (68 kg) on Earth weighs 210 lbs (95 kg) on Neptune. Neptune’s stronger gravitational pull causes this increase in weight. The force of gravity on Neptune exerts 557.5 N (125.5 lbf) on a 50 kg (110.2 lb) person. Neptune has a mass 17.15 times greater than Earth’s mass. Neptune’s larger size and lower density result in higher surface gravity than Earth. A person’s mass remains constant between Earth and Neptune, but the gravitational acceleration differs. Weight equals mass multiplied by gravitational acceleration. Neptune’s higher gravitational acceleration causes increased weight for objects and people on its surface.