Neptune is more than 30 times as far from the Sun as Earth and is the only planet in our solar system not visible to the naked eye and the first predicted by mathematics before its discovery. In 2011 Neptune completed its first 165-year orbit since its discovery in 1846. NASA’s Voyager 2 is the only spacecraft to have visited Neptune up close. It flew past in 1989 on its way out of the solar system.
- Neptune is about four times wider than Earth. If Earth were a large apple, Neptune would be the size of a basketball.
- Neptune orbits our Sun, a star, and is the eighth planet from the Sun at a distance of about 2.8 billion miles (4.5 billion kilometers).
- Neptune takes about 16 hours to rotate once (a Neptunian day), and about 165 Earth years to orbit the sun (a Neptunian year).
- Neptune is an ice giant. Most of its mass is a hot, dense fluid of “icy” materials – water, methane and ammonia – above a small rocky core.
- Neptune’s atmosphere is made up mostly of molecular hydrogen, atomic helium and methane.
- Neptune has 14 known moons which are named after sea gods and nymphs in Greek mythology.
- Neptune has at least five main rings and four more ring arcs, which are clumps of dust and debris likely formed by the gravity of a nearby moon.
- Voyager 2 is the only spacecraft to have visited Neptune. No spacecraft has orbited this distant planet to study it at length and up close.
- Neptune cannot support life as we know it.
- Because of dwarf planet Pluto’s elliptical orbit, Pluto is sometimes closer to the Sun (and us) than Neptune is.
- Even though Neptune is the farthest planet from our Sun, it’s a frequent stop in pop culture and fiction. The planet served as the backdrop for the 1997 science fiction horror film “Event Horizon,” while in the cartoon series “Futurama,” the character Robot Santa Claus has his home base on Neptune’s north pole. “Dr. Who” fans will remember that an episode entitled “Sleep No More” is set on a space station orbiting Neptune. And in the “Star Trek: Enterprise” pilot episode, “Broken Bow,” viewers learn that at warp 4.5 speed, it is possible to fly to Neptune and back to Earth in six minutes.
One popular myth that I was only made aware of a few years ago is that of Nibiru, a supposed planet that some claimed would collide with Earth at the end of the year 2012. But despite the buzz, there’s no scientific evidence supporting the alleged planet’s existence and, of course, our planet survived 2012 without absorbing a massive impact.
The story began in 1976, when Zecharia Sitchin wrote “The Twelfth Planet,” a book which used Stitchin’s own unique translation of Sumerian cuneiform to identify a planet, Nibiru, orbiting the sun every 3,600 years. Several years later, Nancy Lieder, a self-described psychic, announced that the aliens she claimed to channel had warned her this planet would collide with Earth in 2003. After a collision-free year, the date was moved back to 2012, where it was linked to the close of the Mayan long-count period. A planet with an orbit so eccentric that it took 3,600 years to orbit the sun would create instabilities inside our 4.5-billion-year-old solar system.
After only a few trips, its gravity would have significantly disrupted the other planets, whose own gravitational pushes would have changed the hypothetical world’s orbit significantly. According to the information available, a planet with a 3,600-year-long orbit that was due to impact Earth in 2012 should be available to the naked eye. Easily performed calculations show that, by April 2012, it would have been brighter than the faintest stars viewed from a city, and almost as bright as Mars at its dimmest. This would have made it visible to astronomers everywhere.
However; a planet called Nibiru, although not associated with Earth’s doomsday, featured briefly in the 2013 Star Trek film installment Star Trek Into Darkness. The planet appears in the opening scenes as a home of savage tribesmen and a supervolcano about to erupt. The planet, covered by a red jungle and an ocean deep enough to comfortably hide the Enterprise spaceship, is a target of exploration by the crew led by Captain James Kirk. However, things quickly go awry after Spock gets stranded on the super volcano while trying to stop the eruption, prompting the Captain to break the Prime Directive, which prohibits Star Trek explorers from interacting with alien civilizations.
Here are five fascinating facts about our neighbours in the solar system – Mars.
1. Mars Had Water In The Ancient Past: We’ve been debating for centuries about whether Mars had life or not. In fact, the astronomer Percival Lowell misinterpreted observations of “canali” — the Italian word for channels — on the planet as evidence of alien-made canals. It turned out Lowell’s observations were hampered by poor telescope optics of his day, and the canals he saw were optical illusions. That said, several spacecraft have spotted other signs of ancient water — channels grooved in the terrain and rocks that only could have formed in the presence of water, for example.
2. Mars Has Frozen Water Today: We’re very interested in the question of water because it implies habitability; simply put, life as we know it is more likely to exist with water there. In fact, the Curiosity rover’s mandate on Mars right now is to search for habitable environments (in the past or present). Mars has a thin atmosphere that does not allow water to flow or remain in large quantities on the surface, but we know for sure that there is ice at the poles — and possibly frosty locations elsewhere on the planet. The question is if the ice is capable of melting enough water in the summer long enough to support any microbes.
3. Mars Used To Have A Thicker Atmosphere: For water to flow in the past, the Red Planet needs more atmosphere. So something must have changed in the past few billion years. What? It is thought that the Sun’s energy striking the atmosphere must have “stripped” the lighter forms of hydrogen from the top, scattering the molecules into space. Over long periods of time, this would lessen the amount of atmosphere near Mars. This question is being investigated in more detail with NASA’s Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft.
4. Mars Has Two Moons – And One Of Them Is Doomed: The planet has two asteroid-like moons called Phobos and Deimos. Because they have compositions that are similar to asteroids found elsewhere in the Solar System, according to NASA, most scientists believe the Red Planet’s gravity snatched the moons long ago and forced them into orbit. But in the life of the Solar System, Phobos has a pretty short lifetime. In about 30 million to 50 million years, Phobos is going to crash into Mars’ surface or rip apart because the tidal force of the planet will prove too much to resist.
5. We Have Pieces Of Mars On Earth: Remember the low gravity on Mars that we talked about? In the past, the planet has been hit by large asteroids — just like Earth. Most of the debris fell back on the planet, but some of it was ejected into space. That sparked an incredible journey where the debris moved around the Solar System and in some cases, landed on Earth. The technical name for these meteorites is called SNC (Shergottites, Nakhlites, Chassignites — types of geologic composition). Gases trapped in some of these meteorites has been practically identical to what NASA’s Viking landers sampled on the Red Planet in the 1970s and 1980s.
Five years ago today, we started to appreciate just how remarkable Pluto really is. The distant dwarf planet had been a frigid enigma since its 1930 discovery, remaining a fuzzy blob even in photos captured by the powerful Hubble Space Telescope. But everything changed on July 14, 2015, when NASA’s New Horizons spacecraft zoomed within 7,800 miles (12,550 kilometers) of Pluto’s icy surface.
New Horizons observed a large, young, heart-shaped region of ice on Pluto and found mountains made of water ice that may float on top of nitrogen ice. It discovered large chasms on Charon and found that its north pole was covered with reddish material that had escaped from Pluto’s atmosphere. The historic flyby completed the initial reconnaissance of the solar system’s nine traditionally recognized planets and revealed a stunning complexity and diversity of terrain, from nitrogen glaciers to towering mountains of rock-hard water ice.
The $720 million New Horizons mission launched in January 2006, speeding away from Earth at a record-breaking 36,400 mph (58,580 km/h). Even at that blistering pace, it still took the probe 9.5 years to reach Pluto, which was about 3 billion miles (5 billion km) from Earth on the day of the flyby. And in the home stretch of that deep-space trek, New Horizons suffered a glitch that threatened to scuttle the epic encounter entirely. A mere three days after the glitch, New Horizons photographed a stunning sight: a huge, heart-shaped feature on Pluto’s reddish surface. Pluto’s now-iconic heart came into sharper and sharper focus over the ensuing days, as did the rest of the dwarf planet’s “encounter hemisphere” (the side that New Horizons flew over).