Este diagrama compara nosso sistema solar a Kepler-22, o primeiro sistema estelar com uma "zona habitável" descoberto pela missão Kepler, da NASA. A zona habitável é agradável região ao redor de uma estrela onde as temperaturas são adequadas à existência de água em estado líquido. A água nesse estado é essencial à vida na Terra.
A estrela Kepler-22 é um pouco menor do que o nosso Sol, logo, sua zona habitável está ligeiramente mais próxima a ela. O diagrama mostra uma concepção artística do planeta que orbita confortavelmente a zona habitável, semelhante àquela na qual a Terra circunda o Sol. Kepler-22b tem um ano orbital de 289 dias, não muito menor que o da Terra, de 365 dias.
A estrela Kepler-22 é um pouco menor do que o nosso Sol, logo, sua zona habitável está ligeiramente mais próxima a ela. O diagrama mostra uma concepção artística do planeta que orbita confortavelmente a zona habitável, semelhante àquela na qual a Terra circunda o Sol. Kepler-22b tem um ano orbital de 289 dias, não muito menor que o da Terra, de 365 dias.
O planeta é o menor de quem se tem notícia a orbitar o centro da zona habitável de uma estrela semelhante ao Sol. Ele tem cerca de 2,4 vezes o tamanho da Terra.
A missão Kepler descobriu, até agora mais de 1.000 outros novos candidatos a planeta, quase o dobro da contagem anterior. Dez desses candidatos têm tamanho aproximado ao da Terra e orbitam na zona habitável de suas estrelas-mães. Os candidatos necessitam de observações posteriores para se determinar se são de fato planetas.
O planeta cuja existência acaba de ser confirmada, Kepler-22b, tem cerca de 2,4 vezes o raio da Terra. Os Cientistas não sabem ainda se Kepler-22b tem uma composição predominantemente rochosa, gasosa ou líquida, mas sua descoberta é mais um passo na busca por planetas semelhantes à Terra.
Pesquisas anteriores apontavam para a existência de planetas com tamanho similar ao da Terra em zonas habitáveis, mas não foi possível obter uma confirmação. Dois outros pequenos planetas orbitando estrelas menores e mais frias do que o nosso Sol foram confirmados recentemente bem nos limites da zona habitável, com órbitas que se assemelhavam mais às de Vênus e Marte.
"Este é um grande marco na jornada em busca da irmã gêmea da Terra," disse Douglas Hudgins, cientista do programa Kepler na sede da NASA em Washington. "Os resultados da Kepler continuam demonstrando a importância das missões científicas da NASA, que buscam responder algumas das maiores questões a respeito de nosso lugar no universo."
A missão Kepler descobre planetas e candidatos a planeta através da medição das variações no brilho de mais de 150.000 estrelas (o que é uma quantidade irrisória em termos astronômicos), à procura de planetas que passam diante delas, ou as "transitam". A Kepler necessita de ao menos três trânsitos, ou passagens para identificar um sinal como planeta.
"A sorte nos sorriu com a detecção desse planeta," disse William Borucki, principal investigador da Kepler no Centro Ames de Pesquisas da NASA em Moffett Field, Califórnia., que chefiou a equipe descobridora de Kepler-22b. "O primeiro trânsito foi captado três dias após nós termos declarado que a espaçonave estava pronta para entrar em operação. Nós vimos o terceiro trânsito, que define a existência do planeta nas férias de 2010."
A equipe de cientistas da Kepler emprega telescópios baseados no solo e o Telescópio Espacial Spitzer para revisar as observações de candidatos a planeta descobertos pela espaçonave. O campo estelar que a Kepler observa nas constelações do Cisne e da Lira só é visível através observações com telescópios baseados no solo, entre a primavera (no hemisfério norte), e o início do outono. Os dados dessas outras observações ajudam a determinar quais candidatos podem ser confirmados como planetas.
Kepler-22b está localizado a 600 anos-luz de distância da Terra. Embora o planeta seja maior do que a Terra, sua órbita de 290 dias ao redor de uma estrela semelhante ao Sol se parece com a do nosso mundo. A estrela-mãe do planeta pertence à mesma classe de estrelas do nosso Sol, chamada Tipo G, embora seja ligeiramente menor e mais fria.
Dos 54 candidatos a planeta em zonas habitáveis relatados em fevereiro de 2011, Kepler-22b é o primeiro a ser confirmado. Essa conquista será publicada em The Astrophysical Journal.
A equipe da Kepler fez até agora 1.094 descobertas de novos candidatos
a planeta. Desde a divulgação do ultimo catálogo, em Fevereiro, o número de
candidatos a planeta identificados pela Kepler cresceu 89 %, chegando agora ao
total de 2.326. Desses, 207 têm aproximadamente o tamanho da Terra, 680 têm
tamanho maior que o da Terra, 1.181 são de dimensões equivalentes às de Netuno,
203 equivalem ao tamanho de Júpiter e 55 são maiores do que este.
No início, a missão Kepler observou vários grandes planetas em
órbitas pequenas, relatadas no relatório de fevereiro. Tendo tido mais tempo
para observar três trânsitos de planetas com períodos orbitais mais longos, os
novos dados indicam que planetas com tamanho entre uma e quatro vezes o da Terra
podem ser abundantes na galáxia.
Há 48 candidatos a planeta
nas zonas habitáveis de suas estrelas.
"O enorme crescimento no número de candidatos com
tamanho equivalente ao da Terra mostra que estamos na direção certa para
encontrar os planetas para cuja busca a
Kepler foi idealizada: os que não só têm
o tamanho aproximado da Terra, mas que também são potencialmente habitáveis,"
disse Natalie Batalha, Kepler delegado da equipe científica da Kepler na
Universidade Estadual de San Jose, em San Jose, Califórnia. "Quanto mais
dados coletarmos, mais aguçado será o nosso olhar na busca dos menores planetas
com períodos orbitais mais longos."
This diagram compares our own solar system to Kepler-22, a star system containing the first "habitable zone" planet discovered by NASA's Kepler mission. The habitable zone is the sweet spot around a star where temperatures are right for water to exist in its liquid form. Liquid water is essential for life on Earth.
Kepler-22's star is a bit smaller than our sun, so its habitable zone is slightly closer in. The diagram shows an artist's rendering of the planet comfortably orbiting within the habitable zone, similar to where Earth circles the sun. Kepler-22b has a yearly orbit of 289 days. The planet is the smallest known to orbit in the middle of the habitable zone of a sun-like star. It's about 2.4 times the size of Earth.
Kepler-22's star is a bit smaller than our sun, so its habitable zone is slightly closer in. The diagram shows an artist's rendering of the planet comfortably orbiting within the habitable zone, similar to where Earth circles the sun. Kepler-22b has a yearly orbit of 289 days. The planet is the smallest known to orbit in the middle of the habitable zone of a sun-like star. It's about 2.4 times the size of Earth.
NASA's Kepler mission has confirmed its first planet in the "habitable zone," the region where liquid water could exist on a planet’s surface. Kepler also has discovered more than 1,000 new planet candidates, nearly doubling its previously known count. Ten of these candidates are near-Earth-size and orbit in the habitable zone of their host star. Candidates require follow-up observations to verify they are actual planets.
The newly confirmed planet, Kepler-22b, is the smallest yet found to orbit in the middle of the habitable zone of a star similar to our sun. The planet is about 2.4 times the radius of Earth. Scientists don't yet know if Kepler-22b has a predominantly rocky, gaseous or liquid composition, but its discovery is a step closer to finding Earth-like planets.
Previous research hinted at the existence of near-Earth-size planets in habitable zones, but clear confirmation proved elusive. Two other small planets orbiting stars smaller and cooler than our sun recently were confirmed on the very edges of the habitable zone, with orbits more closely resembling those of Venus and Mars.
"This is a major milestone on the road to finding Earth's twin," said Douglas Hudgins, Kepler program scientist at NASA Headquarters in Washington. "Kepler's results continue to demonstrate the importance of NASA's science missions, which aim to answer some of the biggest questions about our place in the universe."
Kepler discovers planets and planet candidates by measuring dips in the brightness of more than 150,000 stars to search for planets that cross in front, or "transit," the stars. Kepler requires at least three transits to verify a signal as a planet.
"Fortune smiled upon us with the detection of this planet," said William Borucki, Kepler principal investigator at NASA Ames Research Center at Moffett Field, Calif., who led the team that discovered Kepler-22b. "The first transit was captured just three days after we declared the spacecraft operationally ready. We witnessed the defining third transit over the 2010 holiday season."
The Kepler science team uses ground-based telescopes and the Spitzer Space Telescope to review observations on planet candidates the spacecraft finds. The star field that Kepler observes in the constellations Cygnus and Lyra can only be seen from ground-based observatories in spring through early fall. The data from these other observations help determine which candidates can be validated as planets.
Kepler-22b is located 600 light-years away. While the planet is larger than Earth, its orbit of 290 days around a sun-like star resembles that of our world. The planet's host star belongs to the same class as our sun, called G-type, although it is slightly smaller and cooler.
Of the 54 habitable zone planet candidates reported in February 2011, Kepler-22b is the first to be confirmed. This milestone will be published in The Astrophysical Journal.
The Kepler team is hosting its inaugural science conference at Ames Dec. 5-9, announcing 1,094 new planet candidate discoveries. Since the last catalog was released in February, the number of planet candidates identified by Kepler has increased by 89 percent and now totals 2,326. Of these, 207 are approximately Earth-size, 680 are super Earth-size, 1,181 are Neptune-size, 203 are Jupiter-size and 55 are larger than Jupiter.
The findings, based on observations conducted May 2009 to September 2010, show a dramatic increase in the numbers of smaller-size planet candidates.
Kepler observed many large planets in small orbits early in its mission, which were reflected in the February data release. Having had more time to observe three transits of planets with longer orbital periods, the new data suggest that planets one to four times the size of Earth may be abundant in the galaxy.
The number of Earth-size and super Earth-size candidates has increased by more than 200 and 140 percent since February, respectively.
There are 48 planet candidates in their star's habitable zone. While this is a decrease from the 54 reported in February, the Kepler team has applied a stricter definition of what constitutes a habitable zone in the new catalog, to account for the warming effect of atmospheres, which would move the zone away from the star, out to longer orbital periods.
"The tremendous growth in the number of Earth-size candidates tells us that we're honing in on the planets Kepler was designed to detect: those that are not only Earth-size, but also are potentially habitable," said Natalie Batalha, Kepler deputy science team lead at San Jose State University in San Jose, California. "The more data we collect, the keener our eye for finding the smallest planets out at longer orbital periods."
The newly confirmed planet, Kepler-22b, is the smallest yet found to orbit in the middle of the habitable zone of a star similar to our sun. The planet is about 2.4 times the radius of Earth. Scientists don't yet know if Kepler-22b has a predominantly rocky, gaseous or liquid composition, but its discovery is a step closer to finding Earth-like planets.
Previous research hinted at the existence of near-Earth-size planets in habitable zones, but clear confirmation proved elusive. Two other small planets orbiting stars smaller and cooler than our sun recently were confirmed on the very edges of the habitable zone, with orbits more closely resembling those of Venus and Mars.
"This is a major milestone on the road to finding Earth's twin," said Douglas Hudgins, Kepler program scientist at NASA Headquarters in Washington. "Kepler's results continue to demonstrate the importance of NASA's science missions, which aim to answer some of the biggest questions about our place in the universe."
Kepler discovers planets and planet candidates by measuring dips in the brightness of more than 150,000 stars to search for planets that cross in front, or "transit," the stars. Kepler requires at least three transits to verify a signal as a planet.
"Fortune smiled upon us with the detection of this planet," said William Borucki, Kepler principal investigator at NASA Ames Research Center at Moffett Field, Calif., who led the team that discovered Kepler-22b. "The first transit was captured just three days after we declared the spacecraft operationally ready. We witnessed the defining third transit over the 2010 holiday season."
The Kepler science team uses ground-based telescopes and the Spitzer Space Telescope to review observations on planet candidates the spacecraft finds. The star field that Kepler observes in the constellations Cygnus and Lyra can only be seen from ground-based observatories in spring through early fall. The data from these other observations help determine which candidates can be validated as planets.
Kepler-22b is located 600 light-years away. While the planet is larger than Earth, its orbit of 290 days around a sun-like star resembles that of our world. The planet's host star belongs to the same class as our sun, called G-type, although it is slightly smaller and cooler.
Of the 54 habitable zone planet candidates reported in February 2011, Kepler-22b is the first to be confirmed. This milestone will be published in The Astrophysical Journal.
The Kepler team is hosting its inaugural science conference at Ames Dec. 5-9, announcing 1,094 new planet candidate discoveries. Since the last catalog was released in February, the number of planet candidates identified by Kepler has increased by 89 percent and now totals 2,326. Of these, 207 are approximately Earth-size, 680 are super Earth-size, 1,181 are Neptune-size, 203 are Jupiter-size and 55 are larger than Jupiter.
The findings, based on observations conducted May 2009 to September 2010, show a dramatic increase in the numbers of smaller-size planet candidates.
Kepler observed many large planets in small orbits early in its mission, which were reflected in the February data release. Having had more time to observe three transits of planets with longer orbital periods, the new data suggest that planets one to four times the size of Earth may be abundant in the galaxy.
The number of Earth-size and super Earth-size candidates has increased by more than 200 and 140 percent since February, respectively.
There are 48 planet candidates in their star's habitable zone. While this is a decrease from the 54 reported in February, the Kepler team has applied a stricter definition of what constitutes a habitable zone in the new catalog, to account for the warming effect of atmospheres, which would move the zone away from the star, out to longer orbital periods.
"The tremendous growth in the number of Earth-size candidates tells us that we're honing in on the planets Kepler was designed to detect: those that are not only Earth-size, but also are potentially habitable," said Natalie Batalha, Kepler deputy science team lead at San Jose State University in San Jose, California. "The more data we collect, the keener our eye for finding the smallest planets out at longer orbital periods."
Kepler 22-b Planet Confirmed
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