This program unpacks Playstation 3 Theme files (.p3t) so that you can touch-up an existing theme to your likings or use a certain wallpaper from it (as many themes have multiple). But remember, if you use content from another theme and release it, be sure to give credit!
Download p3textractor.zip from above. Extract the files to a folder with a program such as WinZip or WinRAR. Now there are multiple ways to extract the theme.
The first way is to simply open the p3t file with p3textractor.exe. If you don’t know how to do this, right click the p3t file and select Open With. Alternatively, open the p3t file and it will ask you to select a program to open with. Click Browse and find p3textractor.exe from where you previously extracted it to. It will open CMD and extract the theme to extracted.[filename]. After that, all you need to do for any future p3t files is open them and it will extract.
The second way is very simple. Just drag the p3t file to p3textractor.exe. It will open CMD and extract the theme to extracted.[filename].
For the third way, first put the p3t file you want to extract into the same folder as p3textractor.exe. Open CMD and browse to the folder with p3extractor.exe. Enter the following: p3textractor filename.p3t [destination path]Replace filename with the name of the p3t file, and replace [destination path] with the name of the folder you want the files to be extracted to. A destination path is not required. By default it will extract to extracted.filename.
This program unpacks Playstation 3 Theme files (.p3t) so that you can touch-up an existing theme to your likings or use a certain wallpaper from it (as many themes have multiple). But remember, if you use content from another theme and release it, be sure to give credit!
Download p3textractor.zip from above. Extract the files to a folder with a program such as WinZip or WinRAR. Now there are multiple ways to extract the theme.
The first way is to simply open the p3t file with p3textractor.exe. If you don’t know how to do this, right click the p3t file and select Open With. Alternatively, open the p3t file and it will ask you to select a program to open with. Click Browse and find p3textractor.exe from where you previously extracted it to. It will open CMD and extract the theme to extracted.[filename]. After that, all you need to do for any future p3t files is open them and it will extract.
The second way is very simple. Just drag the p3t file to p3textractor.exe. It will open CMD and extract the theme to extracted.[filename].
For the third way, first put the p3t file you want to extract into the same folder as p3textractor.exe. Open CMD and browse to the folder with p3extractor.exe. Enter the following: p3textractor filename.p3t [destination path]Replace filename with the name of the p3t file, and replace [destination path] with the name of the folder you want the files to be extracted to. A destination path is not required. By default it will extract to extracted.filename.
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Iron Maiden are an English heavy metal band formed in Leyton, East London, in 1975 by bassist and primary songwriter Steve Harris. Although fluid in the early years of the band, the line-up for most of the band's history has consisted of Harris, lead vocalist Bruce Dickinson, drummer Nicko McBrain, and guitarists Dave Murray, Adrian Smith and Janick Gers. As pioneers of the new wave of British heavy metal movement, Iron Maiden released a series of UK and US Platinum and Gold albums, including 1980's debut album, 1981's Killers, and 1982's The Number of the Beast – its first album with Bruce Dickinson, who in 1981 replaced Paul Di'Anno as lead singer. The addition of Dickinson was a turning point in their career, establishing them as one of heavy metal's most important bands. The Number of the Beast is among the most popular heavy metal albums of all time, having sold almost 20 million copies worldwide.
After some turbulence in the 1990s, the return of lead vocalist Bruce Dickinson and guitarist Adrian Smith in 1999 saw the band undergo a resurgence in popularity, with a series of new albums and highly successful tours. Their three most recent albums — The Final Frontier (2010), The Book of Souls (2015), and Senjutsu (2021) — have all reached number 1 in more than 25 countries. Iron Maiden have sold over 130 million copies of their albums worldwide and have obtained over 600 certifications. The band is considered to be one of the most influential and revered rock bands of all time. They have received multiple industry awards, including the Grammy and Brit Awards, and are also a permanent part of the Rock and Roll Hall of Fame.
The band have released 41 albums, including 17 studio albums, 13 live albums, four EPs and seven compilations. They have also released 47 singles and 20 video albums, and two video games. Iron Maiden's lyrics cover such topics as history, literature, war, mythology, dark fantasy, science fiction, society and religion. As of October 2019[update], the band have played 2,500 live shows. For over 40 years the band have featured their signature mascot, "Eddie", on the covers of almost all of their releases.
The Cart and Horses Pub, located in Maryland Point, Stratford, was where Iron Maiden played some of their first shows in 1976. The building was officially named "The Birthplace of Iron Maiden".[2]
Iron Maiden were formed on Christmas Day, 25 December 1975, by bassist Steve Harris shortly after he left his previous group, Smiler. Harris attributed the band's name to a film adaptation of The Man in the Iron Mask from the novel by Alexandre Dumas, as the title reminded him of the iron maiden torture device.[3] They originally used the name Ash Mountain, but most of the band members preferred the name Iron Maiden. After months of rehearsal, Iron Maiden made their debut at St. Nicks Hall in Poplar on 1 May 1976,[4] before taking up a semi-residency at the Cart and Horses Pub in Maryland, Stratford.[5] The original line-up was short-lived, with vocalist Paul Day being the first to go as, according to Harris, he lacked "energy or charisma on stage".[6] He was replaced by Dennis Wilcock, a Kiss fan who used makeup and fake blood during live performances.[6] Wilcock's friend, guitarist Dave Murray, was invited to join, much to the dismay of the band's guitarists Dave Sullivan and Terry Rance.[7] Their frustration led Harris to temporarily disband Iron Maiden in 1976,[7] though the group reformed soon after with Murray as the sole guitarist. Harris and Murray remain the band's longest-serving members and have performed on all of their releases.
Dave Murray and Steve Harris in 2008. Harris and Murray are the only members to have performed on all of the band's albums.
Iron Maiden recruited another guitarist in 1977, Bob Sawyer, who was sacked for embarrassing the band on stage by pretending to play guitar with his teeth.[8] Tension ensued again, causing a rift between Murray and Wilcock, who convinced Harris to fire Murray,[9] as well as original drummer Ron Matthews.[4] A new line-up was put together, including future Cutting Crew member Tony Moore on keyboards, Terry Wapram on guitar and drummer Barry Purkis (better known today as Thunderstick). After a single gig with the band in January 1978, Moore was asked to leave as Harris decided keyboards did not suit the band's sound.[10] Dave Murray rejoined in late March 1978, and when Terry Wapram disapproved he was sacked. A few weeks later, Dennis Wilcock decided to leave Iron Maiden to form his own band, V1, with Wapram, and drummer Barry Purkis also left. Doug Sampson was at Dennis' and Thunderstick's last gig, and joined the band afterwards.
Harris, Murray and Sampson spent the summer and autumn of 1978 rehearsing while they searched for a singer to complete the band's new line-up.[11] A chance meeting at the Red Lion, a pub in Leytonstone, in November 1978 evolved into a successful audition for vocalist Paul Di'Anno.[12] Steve Harris said, "There's sort of a quality in Paul's voice, a raspiness in his voice, or whatever you want to call it, that just gave it this great edge".[13] At this time, Murray would typically act as their sole guitarist, with Harris commenting, "Davey was so good he could do a lot of it on his own. The plan was always to get a second guitarist in, but finding one that could match Davey was really difficult".[14]
Record contract and early releases (1978–1981)[edit]
On New Year's Eve, 1978, Iron Maiden recorded a four-song demo at Spaceward Studios in Cambridge.[15] Hoping the recording would help them secure more gigs,[15] the band gave a copy to Neal Kay, who, at the time, was managing a heavy metal club called "Bandwagon Heavy Metal Soundhouse".[16] After hearing the tape, Kay began playing the demo regularly at the Bandwagon, and one of the songs, "Prowler", eventually went to number 1 in the Soundhouse charts, which were published weekly in Sounds magazine.[17] A copy was also acquired by Rod Smallwood, who soon became the band's manager.[18] As Iron Maiden's popularity increased, they released the demo on their own record label as The Soundhouse Tapes, named after the club.[19] Featuring only three tracks (one song, "Strange World", was excluded as the band were unsatisfied with its production),[20] all 5,000 copies sold out within weeks.[17]
In December 1979, the band secured a major record deal with EMI[21] and asked Dave Murray's childhood friend, Adrian Smith of Urchin, to join the group as their second guitarist.[22] Busy with his own band, Smith declined and Dennis Stratton was hired instead.[23] Shortly after, Doug Sampson left due to health issues and was replaced by ex-Samson drummer Clive Burr at Stratton's suggestion on 26 December 1979.[24] Iron Maiden's first appearance on an EMI album was on the Metal for Muthas compilation (released on 15 February 1980) with two early versions of "Sanctuary" and "Wrathchild".[25] The release led to a tour including several other bands linked with the new wave of British heavy metal movement.[26]
Iron Maiden released their self-titled album in 1980, which debuted at number 4 in the UK Albums Chart.[27] In addition to the title track, the album included other early favourites such as "Running Free", "Transylvania", "Phantom of the Opera" and "Sanctuary" – which was not on the original UK release, but appeared on the US version and subsequent remasters. The band embarked on a headline tour of the UK, before opening for Kiss on their 1980 Unmasked Tour's European leg as well as supporting Judas Priest on select dates. After the Kiss tour, Dennis Stratton was dismissed from the band as a result of creative and personal differences,[28] and was replaced by Smith in October 1980. In December, the band played at the Rainbow Theatre in London, where their first live video was filmed. Live at the Rainbow was released in May 1981, and "Iron Maiden" and "Wrathchild" from this video received heavy rotation on MTV during its first hours on the air as the first metal videos ever.[29][30][31]
In 1981, Iron Maiden released their second studio album, Killers. Although many tracks were written prior to their debut release, it had two new songs: "Prodigal Son" and "Murders in the Rue Morgue"[32] (the latter's title was taken from the short story by Edgar Allan Poe).[33] Unsatisfied with the production on their debut album,[34] the band hired veteran producer Martin Birch,[35] who would continue to work with Iron Maiden until his retirement in 1992.[36] The record was followed by the band's first world tour; their debut performance in the United States, opening for Judas Priest at The Aladdin Casino in Las Vegas. Killers marked the band's USA album charts debut, reaching number 78 on the Billboard 200,[37] and they booked 132 shows to promote the album, including their first concert in Belgrade, Yugoslavia.[38] During the summer, Iron Maiden played several festivals in Europe, including at the Golden Summernights 1981 festivals at Zeppelinfeld in Nuremberg in front of 100,000 people.[30]
By 1981, Paul Di'Anno was demonstrating increasingly erratic behaviour, particularly due to his drug usage,[4] about which Di'Anno comments, "It wasn't just that I was snorting a bit of coke, though; I was just going for it non-stop, 24 hours a day, every day ... the band had commitments piling up that went on for months, years, and I just couldn't see my way to the end of it. I knew I'd never last the whole tour. It was too much".[39] Di'Anno was dismissed following the Killer World Tour,[40] and the band had already selected his replacement.[41] After a meeting with Rod Smallwood at the Reading Festival,[42]Bruce Dickinson, formerly of Samson, auditioned for Iron Maiden in September 1981 and was immediately hired.[41] The following month, Dickinson went out on the road with the band on a small headlining tour in Italy and a one-off show at the Rainbow Theatre in the UK.[40] For the last show, and in anticipation of their forthcoming album, the band played "Children of the Damned" and "22 Acacia Avenue", introducing fans to their new material.[43]
In 1982, Iron Maiden released their third studio album, The Number of the Beast, which became the band's first number 1 record on the UK Albums Chart,[44] was a Top 10 hit in many other countries and reached number 33 on the Billboard 200.[37][45] At the time, Dickinson was in the midst of legal difficulties with Samson's management and was not permitted to add his name to any of the songwriting credits, although he still made what he described as a "moral contribution" to "Children of the Damned", "The Prisoner" and "Run to the Hills".[46] The band embarked on a world tour, dubbed The Beast on the Road, with shows in North America, Japan, Australia and Europe, including a headline appearance for 40,000 people at the Reading Festival. Iron Maiden played 188 shows in 10 months.[30] The Beast on the Road's US leg proved controversial when an American conservative political lobbying group claimed Iron Maiden were Satanic because of the new album's title track and "demonic" cover art,[45] and a group of Christian activists destroyed Iron Maiden records in protest.[47] Dickinson later said the band treated this as "silliness"[48] and the demonstrations in fact gave them "loads of publicity".[4]The Number of the Beast sold 2.5 million copies in its first year, 14 million by 2010, and 20 million by 2022.[49][50][51][52]
Nicko McBrain has been Iron Maiden's drummer since 1982.
In December 1982, drummer Clive Burr was fired from the band and replaced by Nicko McBrain, who previously played for Trust.[53] Although Harris said the dismissal took place because his live performances were affected by offstage activities,[54] Burr later claimed he was unfairly ousted from the band.[55] The band then recorded the first of three consecutive albums at Compass Point Studios in the Bahamas.[56] In 1983, they released their fourth studio album, Piece of Mind, which reached the number 3 spot in the UK[57] and number 14 on the Billboard 200.[37]Piece of Mind features the singles "The Trooper" and "Flight of Icarus", the latter being one of the band's few songs to gain substantial airplay in the US.[58] Iron Maiden played 147 concerts in Europe and North America as a part of the World Piece Tour. This was also their first major North American tour as headliners, selling out Madison Square Garden with a crowd of 20,000.[30][59]
After the success of Piece of Mind and its supporting tour, the band released their fifth studio album, Powerslave, on 9 September 1984. The album features the singles "2 Minutes to Midnight" and "Aces High", the title track, and "Rime of the Ancient Mariner" (based on Samuel Taylor Coleridge's poem of the same name).[60]Powerslave was another chart success, reaching number 12 on the Billboard 200[37] and eventually number 1 in the UK.[61][62][63] Band's fifth studio album sold over 4 million copies in its first year after the premiere.[64] The tour following the album, called World Slavery Tour, was the band's largest to date with 193 shows in 28 countries over 13 months,[60] playing to an estimated 3,500,000 people.[65][66] Many shows were played back to back in the same city, such as in Long Beach, California, where the band played four consecutive concerts at Long Beach Arena for a combined audience of 54,000 fans.[67] Iron Maiden also made their debut appearance in South America, where they co-headlined the Rock in Rio festival with Queen for an audience estimated at 350,000–500,000 people.[68][69] The tour started in August 1984 with five shows in Poland. Iron Maiden were the first Western artists to bring full-scale production behind the Iron Curtain. The band's third official video, entitled Behind the Iron Curtain, was released in October 1984. The World Slavery Tour documentary brought footage of the band touring Eastern Europe in 1984, performing shows in the countries visited, Behind the Iron Curtain was the first documentary ever published by a Western artist that showed them touring the countries of Eastern Bloc. The documentary movie was broadcast by MTV and local TV stations around the world.[70]
The tour was physically gruelling for the band, who demanded six months off when it ended (although this was later reduced to four months).[71] This was the first substantial touring break in the group's history, including the cancellation of a proposed supporting tour for the new live album,[72] with Bruce Dickinson threatening to quit unless the tour ended.[73] In October 1985, Iron Maiden released the double live album and home video, Live After Death. A critical and commercial success, it peaked at number 19 on the Billboard 200[37] and number 2 in the UK.[74] The album was recorded at Long Beach Arena and also features additional tracks from four nights at London's Hammersmith Apollo.[75][76] In November 1985, Iron Maiden were named the best rock and metal band in the world and awarded at Public Choice International.[77]
Returning from their time off, the band added different musical elements to their 1986 studio album, Somewhere in Time. These focused on synthesised bass and guitars to add textures and layers to the sound.[78] The release performed well across the world, particularly the single "Wasted Years", but included no writing credits from Dickinson, whose material was rejected by the rest of the band.[79] The album was the band's biggest American chart success to date, reaching number 11 on the Billboard 200[37] and number 2 in the UK charts.[74][80] The Somewhere on Tour was also a success. The band played 157 shows for over two and a half million fans, including eighty-one shows in North America. Once again, Iron Maiden visited Poland, Hungary and Yugoslavia to play for tens of thousands of fans in each country.[81] The experimentation evident on Somewhere in Time continued on their next album, Seventh Son of a Seventh Son, which was released in 1988. A concept album recorded at Musicland Studios in Munich[82] and based on the 1987 novel Seventh Son by Orson Scott Card,[83] it was the band's first record to include keyboards, which were performed by Harris and Smith.[83] Dickinson's enthusiasm was also renewed as his ideas were accepted for this album.[84] Another popular release, it became Iron Maiden's second album to hit number 1 in the UK charts
This program unpacks Playstation 3 Theme files (.p3t) so that you can touch-up an existing theme to your likings or use a certain wallpaper from it (as many themes have multiple). But remember, if you use content from another theme and release it, be sure to give credit!
Download p3textractor.zip from above. Extract the files to a folder with a program such as WinZip or WinRAR. Now there are multiple ways to extract the theme.
The first way is to simply open the p3t file with p3textractor.exe. If you don’t know how to do this, right click the p3t file and select Open With. Alternatively, open the p3t file and it will ask you to select a program to open with. Click Browse and find p3textractor.exe from where you previously extracted it to. It will open CMD and extract the theme to extracted.[filename]. After that, all you need to do for any future p3t files is open them and it will extract.
The second way is very simple. Just drag the p3t file to p3textractor.exe. It will open CMD and extract the theme to extracted.[filename].
For the third way, first put the p3t file you want to extract into the same folder as p3textractor.exe. Open CMD and browse to the folder with p3extractor.exe. Enter the following: p3textractor filename.p3t [destination path]Replace filename with the name of the p3t file, and replace [destination path] with the name of the folder you want the files to be extracted to. A destination path is not required. By default it will extract to extracted.filename.
This program unpacks Playstation 3 Theme files (.p3t) so that you can touch-up an existing theme to your likings or use a certain wallpaper from it (as many themes have multiple). But remember, if you use content from another theme and release it, be sure to give credit!
Download p3textractor.zip from above. Extract the files to a folder with a program such as WinZip or WinRAR. Now there are multiple ways to extract the theme.
The first way is to simply open the p3t file with p3textractor.exe. If you don’t know how to do this, right click the p3t file and select Open With. Alternatively, open the p3t file and it will ask you to select a program to open with. Click Browse and find p3textractor.exe from where you previously extracted it to. It will open CMD and extract the theme to extracted.[filename]. After that, all you need to do for any future p3t files is open them and it will extract.
The second way is very simple. Just drag the p3t file to p3textractor.exe. It will open CMD and extract the theme to extracted.[filename].
For the third way, first put the p3t file you want to extract into the same folder as p3textractor.exe. Open CMD and browse to the folder with p3extractor.exe. Enter the following: p3textractor filename.p3t [destination path]Replace filename with the name of the p3t file, and replace [destination path] with the name of the folder you want the files to be extracted to. A destination path is not required. By default it will extract to extracted.filename.
This program unpacks Playstation 3 Theme files (.p3t) so that you can touch-up an existing theme to your likings or use a certain wallpaper from it (as many themes have multiple). But remember, if you use content from another theme and release it, be sure to give credit!
Download p3textractor.zip from above. Extract the files to a folder with a program such as WinZip or WinRAR. Now there are multiple ways to extract the theme.
The first way is to simply open the p3t file with p3textractor.exe. If you don’t know how to do this, right click the p3t file and select Open With. Alternatively, open the p3t file and it will ask you to select a program to open with. Click Browse and find p3textractor.exe from where you previously extracted it to. It will open CMD and extract the theme to extracted.[filename]. After that, all you need to do for any future p3t files is open them and it will extract.
The second way is very simple. Just drag the p3t file to p3textractor.exe. It will open CMD and extract the theme to extracted.[filename].
For the third way, first put the p3t file you want to extract into the same folder as p3textractor.exe. Open CMD and browse to the folder with p3extractor.exe. Enter the following: p3textractor filename.p3t [destination path]Replace filename with the name of the p3t file, and replace [destination path] with the name of the folder you want the files to be extracted to. A destination path is not required. By default it will extract to extracted.filename.
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When appropriate, protection levels are automatically sensed, described and categorized.
This program unpacks Playstation 3 Theme files (.p3t) so that you can touch-up an existing theme to your likings or use a certain wallpaper from it (as many themes have multiple). But remember, if you use content from another theme and release it, be sure to give credit!
Download p3textractor.zip from above. Extract the files to a folder with a program such as WinZip or WinRAR. Now there are multiple ways to extract the theme.
The first way is to simply open the p3t file with p3textractor.exe. If you don’t know how to do this, right click the p3t file and select Open With. Alternatively, open the p3t file and it will ask you to select a program to open with. Click Browse and find p3textractor.exe from where you previously extracted it to. It will open CMD and extract the theme to extracted.[filename]. After that, all you need to do for any future p3t files is open them and it will extract.
The second way is very simple. Just drag the p3t file to p3textractor.exe. It will open CMD and extract the theme to extracted.[filename].
For the third way, first put the p3t file you want to extract into the same folder as p3textractor.exe. Open CMD and browse to the folder with p3extractor.exe. Enter the following: p3textractor filename.p3t [destination path]Replace filename with the name of the p3t file, and replace [destination path] with the name of the folder you want the files to be extracted to. A destination path is not required. By default it will extract to extracted.filename.
The word planet comes from the Greek πλανήται (planḗtai) 'wanderers'. In antiquity, this word referred to the Sun, Moon, and five points of light visible to the naked eye that moved across the background of the stars—namely, Mercury, Venus, Mars, Jupiter, and Saturn. Planets have historically had religious associations: multiple cultures identified celestial bodies with gods, and these connections with mythology and folklore persist in the schemes for naming newly discovered Solar System bodies. Earth itself was recognized as a planet when heliocentrism supplanted geocentrism during the 16th and 17th centuries.
With the development of the telescope, the meaning of planet broadened to include objects only visible with assistance: the moons of the planets beyond Earth; the ice giants Uranus and Neptune; Ceres and other bodies later recognized to be part of the asteroid belt; and Pluto, later found to be the largest member of the collection of icy bodies known as the Kuiper belt. The discovery of other large objects in the Kuiper belt, particularly Eris, spurred debate about how exactly to define a planet. In 2006, the International Astronomical Union (IAU) adopted a definition of a planet in the Solar System, placing the four terrestrial planets and the four giant planets in the planet category; Ceres, Pluto, and Eris are in the category of dwarf planet.[2][3][4] Many planetary scientists have nonetheless continued to apply the term planet more broadly, including dwarf planets as well as rounded satellites like the Moon.[5]
Further advances in astronomy led to the discovery of over five thousand planets outside the Solar System, termed exoplanets. These often show unusual features that the Solar System planets do not show, such as hot Jupiters—giant planets that orbit close to their parent stars, like 51 Pegasi b—and extremely eccentric orbits, such as HD 20782 b. The discovery of brown dwarfs and planets larger than Jupiter also spurred debate on the definition, regarding where exactly to draw the line between a planet and a star. Multiple exoplanets have been found to orbit in the habitable zones of their stars (where liquid water can potentially exist on a planetary surface), but Earth remains the only planet known to support life.
It is not known with certainty how planets are formed. The prevailing theory is that they coalesce during the collapse of a nebula into a thin disk of gas and dust. A protostar forms at the core, surrounded by a rotating protoplanetary disk. Through accretion (a process of sticky collision) dust particles in the disk steadily accumulate mass to form ever-larger bodies. Local concentrations of mass known as planetesimals form, and these accelerate the accretion process by drawing in additional material by their gravitational attraction. These concentrations become ever denser until they collapse inward under gravity to form protoplanets.[6] After a planet reaches a mass somewhat larger than Mars's mass, it begins to accumulate an extended atmosphere,[7] greatly increasing the capture rate of the planetesimals by means of atmospheric drag.[8][9] Depending on the accretion history of solids and gas, a giant planet, an ice giant, or a terrestrial planet may result.[10][11][12] It is thought that the regular satellites of Jupiter, Saturn, and Uranus formed in a similar way;[13][14] however, Triton was likely captured by Neptune,[15] and Earth's Moon[16] and Pluto's Charon might have formed in collisions.[17]
When the protostar has grown such that it ignites to form a star, the surviving disk is removed from the inside outward by photoevaporation, the solar wind, Poynting–Robertson drag and other effects.[18][19] Thereafter there still may be many protoplanets orbiting the star or each other, but over time many will collide, either to form a larger, combined protoplanet or release material for other protoplanets to absorb.[20] Those objects that have become massive enough will capture most matter in their orbital neighbourhoods to become planets. Protoplanets that have avoided collisions may become natural satellites of planets through a process of gravitational capture, or remain in belts of other objects to become either dwarf planets or small bodies.[21][22]
The energetic impacts of the smaller planetesimals (as well as radioactive decay) will heat up the growing planet, causing it to at least partially melt. The interior of the planet begins to differentiate by density, with higher density materials sinking toward the core.[23] Smaller terrestrial planets lose most of their atmospheres because of this accretion, but the lost gases can be replaced by outgassing from the mantle and from the subsequent impact of comets[24] (smaller planets will lose any atmosphere they gain through various escape mechanisms[25]).
With the discovery and observation of planetary systems around stars other than the Sun, it is becoming possible to elaborate, revise or even replace this account. The level of metallicity—an astronomical term describing the abundance of chemical elements with an atomic number greater than 2 (helium)—appears to determine the likelihood that a star will have planets.[26][27] Hence, a metal-rich population I star is more likely to have a substantial planetary system than a metal-poor, population II star.[28]
According to the IAU definition, there are eight planets in the Solar System, which are (in increasing distance from the Sun):[2] Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Jupiter is the largest, at 318 Earth masses, whereas Mercury is the smallest, at 0.055 Earth masses.[29]
The planets of the Solar System can be divided into categories based on their composition. Terrestrials are similar to Earth, with bodies largely composed of rock and metal: Mercury, Venus, Earth, and Mars. Earth is the largest terrestrial planet.[30]Giant planets are significantly more massive than the terrestrials: Jupiter, Saturn, Uranus, and Neptune.[30] They differ from the terrestrial planets in composition. The gas giants, Jupiter and Saturn, are primarily composed of hydrogen and helium and are the most massive planets in the Solar System. Saturn is one third as massive as Jupiter, at 95 Earth masses.[31] The ice giants, Uranus and Neptune, are primarily composed of low-boiling-point materials such as water, methane, and ammonia, with thick atmospheres of hydrogen and helium. They have a significantly lower mass than the gas giants (only 14 and 17 Earth masses).[31]
The Sun's, planets', dwarf planets' and moons' size to scale, labelled. Distance of objects is not to scale. The asteroid belt lies between the orbits of Mars and Jupiter, the Kuiper belt lies beyond Neptune's orbit.
Dwarf planets are gravitationally rounded, but have not cleared their orbits of other bodies. In increasing order of average distance from the Sun, the ones generally agreed among astronomers are Ceres, Orcus, Pluto, Haumea, Quaoar, Makemake, Gonggong, Eris, and Sedna.[32][33] Ceres is the largest object in the asteroid belt, located between the orbits of Mars and Jupiter. The other eight all orbit beyond Neptune. Orcus, Pluto, Haumea, Quaoar, and Makemake orbit in the Kuiper belt, which is a second belt of small Solar System bodies beyond the orbit of Neptune. Gonggong and Eris orbit in the scattered disc, which is somewhat further out and, unlike the Kuiper belt, is unstable towards interactions with Neptune. Sedna is the largest known detached object, a population that never comes close enough to the Sun to interact with any of the classical planets; the origins of their orbits are still being debated. All nine are similar to terrestrial planets in having a solid surface, but they are made of ice and rock rather than rock and metal. Moreover, all of them are smaller than Mercury, with Pluto being the largest known dwarf planet and Eris being the most massive.[34][35]
There are at least nineteen planetary-mass moons or satellite planets—moons large enough to take on ellipsoidal shapes:[4]
The Moon, Io, and Europa have compositions similar to the terrestrial planets; the others are made of ice and rock like the dwarf planets, with Tethys being made of almost pure ice. Europa is often considered an icy planet, though, because its surface ice layer makes it difficult to study its interior.[4][36] Ganymede and Titan are larger than Mercury by radius, and Callisto almost equals it, but all three are much less massive. Mimas is the smallest object generally agreed to be a geophysical planet, at about six millionths of Earth's mass, though there are many larger bodies that may not be geophysical planets (e.g. Salacia).[32]
In early 1992, radio astronomers Aleksander Wolszczan and Dale Frail announced the discovery of two planets orbiting the pulsarPSR 1257+12.[40] This discovery was confirmed and is generally considered to be the first definitive detection of exoplanets. Researchers suspect they formed from a disk remnant left over from the supernova that produced the pulsar.[41]
In 2011, the Kepler Space Telescope team reported the discovery of the first Earth-sized exoplanets orbiting a Sun-like star, Kepler-20e and Kepler-20f.[45][46][47] Since that time, more than 100 planets have been identified that are approximately the same size as Earth, 20 of which orbit in the habitable zone of their star—the range of orbits where a terrestrial planet could sustain liquid water on its surface, given enough atmospheric pressure.[48][49][50] One in five Sun-like stars is thought to have an Earth-sized planet in its habitable zone, which suggests that the nearest would be expected to be within 12 light-years distance from Earth.[a] The frequency of occurrence of such terrestrial planets is one of the variables in the Drake equation, which estimates the number of intelligent, communicating civilizations that exist in the Milky Way.[53]
There are types of planets that do not exist in the Solar System: super-Earths and mini-Neptunes, which have masses between that of Earth and Neptune. Objects less than about twice the mass of Earth are expected to be rocky like Earth; beyond that, they become a mixture of volatiles and gas like Neptune.[54] The planet Gliese 581c, with a mass 5.5–10.4 times the mass of Earth,[55] attracted attention upon its discovery for potentially being in the habitable zone,[56] though later studies concluded that it is actually too close to its star to be habitable.[57] Planets more massive than Jupiter are also known, extending seamlessly into the realm of brown dwarfs.[58]
Exoplanets have been found that are much closer to their parent star than any planet in the Solar System is to the Sun. Mercury, the closest planet to the Sun at 0.4 AU, takes 88 days for an orbit, but ultra-short period planets can orbit in less than a day. The Kepler-11 system has five of its planets in shorter orbits than Mercury's, all of them much more massive than Mercury. There are hot Jupiters, such as 51 Pegasi b,[42] that orbit very close to their star and may evaporate to become chthonian planets, which are the leftover cores. There are also exoplanets that are much farther from their star. Neptune is 30 AU from the Sun and takes 165 years to orbit, but there are exoplanets that are thousands of AU from their star and take more than a million years to orbit (e.g. COCONUTS-2b).[59]
Although each planet has unique physical characteristics, a number of broad commonalities do exist among them. Some of these characteristics, such as rings or natural satellites, have only as yet been observed in planets in the Solar System, whereas others are commonly observed in exoplanets.[60]
The orbit of the planet Neptune compared to that of Pluto. Note the elongation of Pluto's orbit in relation to Neptune's (eccentricity), as well as its large angle to the ecliptic (inclination).
In the Solar System, all the planets orbit the Sun in the same direction as the Sun rotates: counter-clockwise as seen from above the Sun's north pole. At least one exoplanet, WASP-17b, has been found to orbit in the opposite direction to its star's rotation.[61] The period of one revolution of a planet's orbit is known as its sidereal period or year.[62] A planet's year depends on its distance from its star; the farther a planet is from its star, the longer the distance it must travel and the slower its speed, since it is less affected by its star's gravity.
No planet's orbit is perfectly circular, and hence the distance of each from the host star varies over the course of its year. The closest approach to its star is called its periastron, or perihelion in the Solar System, whereas its farthest separation from the star is called its apastron (aphelion). As a planet approaches periastron, its speed increases as it trades gravitational potential energy for kinetic energy, just as a falling object on Earth accelerates as it falls. As the planet nears apastron, its speed decreases, just as an object thrown upwards on Earth slows down as it reaches the apex of its trajectory.[63]
Each planet's orbit is delineated by a set of elements:
The eccentricity of an orbit describes the elongation of a planet's elliptical (oval) orbit. Planets with low eccentricities have more circular orbits, whereas planets with high eccentricities have more elliptical orbits. The planets and large moons in the Solar System have relatively low eccentricities, and thus nearly circular orbits.[62] The comets and many Kuiper belt objects, as well as several exoplanets, have very high eccentricities, and thus exceedingly elliptical orbits.[64][65]
The semi-major axis gives the size of the orbit. It is the distance from the midpoint to the longest diameter of its elliptical orbit. This distance is not the same as its apastron, because no planet's orbit has its star at its exact centre.[62]
The inclination of a planet tells how far above or below an established reference plane its orbit is tilted. In the Solar System, the reference plane is the plane of Earth's orbit, called the ecliptic. For exoplanets, the plane, known as the sky plane or plane of the sky, is the plane perpendicular to the observer's line of sight from Earth.[66] The orbits of the eight major planets of the Solar System all lie very close to the ecliptic; however, some smaller objects like Pallas, Pluto, and Eris orbit at far more extreme angles to it, as do comets.[67] The large moons are generally not very inclined to their parent planets' equators, but Earth's Moon, Saturn's Iapetus, and Neptune's Triton are exceptions. Triton is unique among the large moons in that it orbits retrograde, i.e. in the direction opposite to its parent planet's rotation.[68]
The points at which a planet crosses above and below its reference plane are called its ascending and descending nodes.[62] The longitude of the ascending node is the angle between the reference plane's 0 longitude and the planet's ascending node. The argument of periapsis (or perihelion in the Solar System) is the angle between a planet's ascending node and its closest approach to its star.[62]
Earth's axial tilt is about 23.4°. It oscillates between 22.1° and 24.5° on a 41,000-year cycle and is currently decreasing.
Planets have varying degrees of axial tilt; they spin at an angle to the plane of their stars' equators. This causes the amount of light received by each hemisphere to vary over the course of its year; when the northern hemisphere points away from its star, the southern hemisphere points towards it, and vice versa. Each planet therefore has seasons, resulting in changes to the climate over the course of its year. The time at which each hemisphere points farthest or nearest from its star is known as its solstice. Each planet has two in the course of its orbit; when one hemisphere has its summer solstice with its day being the longest, the other has its winter solstice when its day is shortest. The varying amount of light and heat received by each hemisphere creates annual changes in weather patterns for each half of the planet. Jupiter's axial tilt is very small, so its seasonal variation is minimal; Uranus, on the other hand, has an axial tilt so extreme it is virtually on its side, which means that its hemispheres are either continually in sunlight or continually in darkness around the time of its solstices.[69] In the Solar System, Mercury, Venus, Ceres, and Jupiter have very small tilts; Pallas, Uranus, and Pluto have extreme ones; and Earth, Mars, Vesta, Saturn, and Neptune have moderate ones.[70][71][72][73] Among exoplanets, axial tilts are not known for certain, though most hot Jupiters are believed to have a negligible axial tilt as a result of their proximity to their stars.[74] Similarly, the axial tilts of the planetary-mass moons are near zero,[75] with Earth's Moon at 6.687° as the biggest exception;[76] additionally, Callisto's axial tilt varies between 0 and about 2 degrees on timescales of thousands of years.[77]
