Mars and Earth (PT/EN)

 

FEATURE: Marte mais próximo da Terra nos dias 30 e 31 de julho   

Mars closest to Earth on July 30 and 31

©NASA
©NASA

Marte mais próximo da Terra nos dias 30 e 31 de julho

Desde 2003 que Marte e a Terra não estavam tão próximos.

Assim, nos dias 30 e 31 de julho, o planeta vermelho dista de nós cerca de 57,57 milhões de km, sendo que em 2003 a distância foi de 55,76 milhões de km. Em 60.000 anos, esta foi a distância mais curta entre os dois planetas irmãos.

Até à oposição marciana a 15 de setembro de 2035, esta será a altura em que os terceiro e o quarto calhaus a contar o Sol estarão mais perto um do outro.

Mars closest to Earth on July 30 and 31

Since 2003 Mars and the Earth were not so close.

Thus, on 30 and 31 July, the red planet is about 57.57 million km away, and in 2003 the distance was 55.76 million km. In 60,000 years, this was the shortest distance between the two “brothers”.

Until the Martian opposition on September 15, 2035, this will be the time when the third and fourth rocksfrom the Sun will be closer to each other.

MOVIMENTO RETRÓGRADO

Marte irá inverter a sua trajetória no céu no dia 28 de junho de 2018. Durante dois meses Marte terá movimento retrógrado de 28 de junho a 28 de agosto. Será possível ver Marte, um pouco antes da meia-noite, no céu a Sudeste, quase alinhado com os planetas Saturno e Júpiter, brilhará cada vez mais cedo a cada semana que passa.

OPOSIÇÃO

No dia 27 de julho de 2018 pelas 05 horas (hora legal de Portugal Continental e na Região autónoma da Madeira) Marte estará em oposição em que será visível durante toda a noite e observar-se-á mais brilhante e maior, encontrando-se no céu noturno a brilhar com uma magnitude de -2,8 na constelação de Capricórnio.Neste dia, ocorre um evento celeste raro, é quando o planeta vermelho Marte estará alinhado em uma linha reta com o Sol e a Terra.

Este alinhamento cósmico, chamado oposição de Marte ocorre a cada 778 dias ou de dois anos, um mês e 18 dias. A Terra viaja mais rápido, pois encontra-se mais perto do Sol, completando uma volta em 365,25 dias, enquanto Marte é mais distante do Sol e leva 687 dias para viajar.

Vénus e a Terra são alguns planetas que viajam em círculos quase perfeitos, enquanto outros planetas, como Marte e Mercúrio viajam em órbitas mais excêntricas ou elípticas.

Depois de cinco dias da ocorrência deste evento da oposição de Marte, o planeta vermelho Marte estará à distância mínima da Terra.

DISTÂNCIA MÍNIMA DA TERRA

©Observatório Astronómico de Lisboa
©Observatório Astronómico de Lisboa

No dia 31 de julho, Marte estará muito perto de nós!

No período da manhã de dia 31, mais precisamente às 08h48min (em Portugal continental), Marte estará à distância mínima da Terra. A esta hora não será possível observar Marte, pois nesse preciso momento estará abaixo do horizonte.

Marte nasce mais cedo às 20h55min no início da noite, e põe-se de manhã às 06h01min altura em que se deixa de ver. Observar-se-á Marte durante toda a noite como um objeto brilhante avermelhado! O planeta Marte estará mais próximo da Terra e, por isso mesmo, mais brilhante. Este fenómeno acontece de 26 em 26 meses, sempre que a Terra ultrapassa Marte no movimento de translação em torno do Sol (o nosso planeta é mais rápido neste movimento).

Assim, Marte estará aproximadamente apenas a 57,6 milhões de quilómetros da Terra. Será a maior aproximação à Terra desde agosto de 2003!

In Observatório Astronómico de Lisboa

http://oal.ul.pt/efemerides-marcianas-neste-verao-de-2018/

Mars closest to Earth on July 30-31

On July 30-31, 2018, Mars and Earth are closer than since their historically close approach in 2003. Mars was closer in 2003 than in some 60,000 years, and it’s now only slightly farther from Earth now than then. It’s about 35.78 million miles (57.59 million km) away at its closest on July 31 at 08:00 UTC. That time places Mars’ closest approach before sunrise on July 31 for North American time zones – and on July 30 at 10 p.m. Hawaiian Time.

Have you seen Mars yet? You can see it easily with the eye alone as the very bright red “star” in the east every evening, and in the west before dawn.

This July 30-31, 2018 close encounter between the Earth and Mars is the closest until around the time of the Martian opposition on September 15, 2035.

In EarthSky.org

http://earthsky.org/tonight/mars-closest-to-earth-on-july-30-31

The cycle of close and far Martian oppositions

Mars comes closest to Earth every other year, around the time of its opposition, when Earth is sweeping between the sun and Mars. Mars was at opposition on July 27, 2018, and – at this very favorable opposition – Mars was also be at itsbrightest since 2003. Yet Mars is closest to us several days after opposition, during the night of July 30 (morning of July 31) according to clocks in North America.

Why are the dates different? Why was Mars brightest then, although it is closest now? And is now a good time to view Mars through a telescope? For the answers to all of those questions, read this post: Mars closest to Earth on July 30-31.

 

©ClassicalAstronomy.com
©ClassicalAstronomy.com

Oppositions of Mars are far from equal, and this one is a good one. At its closest – July 30-31, 2018 – Mars comes to within 35.78 million miles (57.59 million km) of Earth.

Nearly 60,000 years ago – on September 24, 57,617 B.C. – Mars was only 34.62 million miles (55.72 million km) distant. The opposition of Mars on August 28, 2003 – which brought Mars to 34.65 million miles (55.76 million km) of Earth – was Mars’ closest approach since then. The 2003 record for closeness won’t be broken again until August 29, 2287.

In contrast, the most recent distant opposition of Mars – on March 3, 2012 – placed the planet at 62.62 million miles (100.78 million km) away.

Mars comes closest to Earth about every two years. Earth takes a year to orbit the sun, and Mars takes about two years. So we go between the sun and Mars – bringing Mars closest to us for that two-year period – that often. But Mars is especially close in 2018.

Mars is close in 2018 because its perihelion or closest point to the sun is coming up on September 16, 2018. Earth has a closest and farthest point from the sun, too. We’re closest to the sun every January, and farthest from the sun every July. But the orbit of Earth is very nearly circular, so our distance from the sun doesn’t vary much (only about 3 million miles, or 5 million km). Because Mars’ orbit is more highly elliptical, Mars’ distance from the sun varies more (by about 26 million miles, or 43 million km).

©Guy Ottewell
©Guy Ottewell

Perhaps you can see that – when Mars is closer to the sun around the time we pass between it and the sun – it’s closer than usual to us.

Astronomers call this year’s opposition of Mars a perihelic opposition. The last one was in 2003.

Close (or distant) oppositions of Mars recur in periods of 15 to 17 years. Note that we’re now 15 years past the historically close encounter on August 28, 2003.

Mars’ next extra-close opposition will be September 15, 2035, though – like the 2018 opposition – it won’t be quite as close as the opposition of August, 2003.

Very similar Martian oppositions take place every 79 years (15 + 17 + 15 + 17 + 15 = 79). These 79-year cycles repeat with only a delay of two to five calendar days. The super-close opposition of Mars in the year 2082 will fall on September 1, 2082. But once again, Earth and Mars won’t come as close as they did in August 2003.

There is a more exact cycle of 284 years (79 + 79 + 79 + 15 + 17 + 15 = 284). The Martian opposition that comes 284 years after August 28, 2003, will fall on August 29, 2287. This time around, Mars will come closer to Earth than it did during its close encounter in August 2003.

Because the Martian orbit is becoming more eccentric (flatter), the closest oppositions will actually come closer to Earth, and the farthest oppositions will actually become more distant. The computational wizard Jean Meeus figures that from the years 0 to 3000 A.D., Mars will come closest to Earth on September 8, 2729 (55.65 million kilometers or 34.57 million miles) and farthest away on March 6, 2832 (101.50 million kilometers or 63 million miles).

While the time is at hand, enjoy the close appearance of Mars in Earth’s sky during July and August of 2018.

In EarthSky.org

http://earthsky.org/sky-archive/close-and-far-martian-oppositions

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