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Conjunction: Mars, Venus and Moon

by Stefan Grießinger

Todos sabem que a Via Láctea é parte de um aglomerado, ou uma coleção de galáxias, chamado de Grupo Local.

Nesse aglomerado, a própria Via Láctea e a galáxia de Andrômeda são os membros mais proeminentes, mas existem muitas outras galáxias, galáxias anãs e satélites da nossa Via Láctea.

A  Pequena e a Grande Nuvem de Magalhães talvez sejam os exemplos mais famosos dessas galáxias satélites, e que podem até mesmo serem vistas a olho nu do hemisfério sul da Terra.

Devido à proximidade essas galáxias tornam-se verdadeiros laboratórios astronômicos, onde é possível tentar entender fases importantes da evolução das galáxias, além de entender a sua composição.

Para utilizar de maneira eficiente esse laboratório, os astrônomos usaram o Hubble para pesquisar nebulosas de emissão dentro dessas galáxias.

Uma delas, na verdade são duas, mas que aparecem tão juntas que são nomeadas como se fosse uma, é a NGC 248.

Essa nebulosa tem 60 anos-luz de comprimento, por 20 anos-luz de largura, está localizada a 200 mil anos-luz de distância da Terra na constelação de Tucano.

Essa nebulosa emite um intenso brilho avermelhado graças a estrelas centrais que estão aquecendo o hidrogênio fazendo com que ele brilhe dessa maneira.

Os astrônomos usaram um projeto chamado de Investigação da Evolução do Gás e da Poeira na Pequena Nuvem de Magalhães, ou SMIDGE para pesquisar essa nebulosa e estudar como a sua poeira, é diferente da poeira da Via Láctea.

Além disso, o Hubble ajuda os astrônomos a entender melhor a história de como a galáxia e suas estrelas se formaram numa época no universo em que se tinha uma baixa porcentagem de elementos pesados.

E esses estudos ajudam de forma decisiva a entender toda a evolução das galáxias.

(via https://www.youtube.com/watch?v=Jy5r1raCdDE)

Conjunction: Mars, Venus and Moon

by Stefan Grießinger

This is not just an incredible view of Earth, it’s also a fantastic illustration of the terminator. (No not that one!) The terminator is the moving line that separates the day side from the dark night side of a planetary body. From this vantage point you can make out the gradual transition to darkness that is experienced as twilight on the surface. This image was captured on Aug. 31 by astronaut Jeff Williams (@Astro_Jeff) while on board the ISS.

Ten Interesting facts about Mercury

Mercury is the closest planet to the sun. As such, it circles the sun faster than all the other planets, which is why Romans named it after their swift-footed messenger god. He is the god of financial gain, commerce, eloquence, messages, communication (including divination), travelers, boundaries, luck, trickery and thieves; he also serves as the guide of souls to the underworld

Like Venus, Mercury orbits the Sun within Earth’s orbit as an inferior planet, and never exceeds 28° away from the Sun. When viewed from Earth, this proximity to the Sun means the planet can only be seen near the western or eastern horizon during the early evening or early morning. At this time it may appear as a bright star-like object, but is often far more difficult to observe than Venus. The planet telescopically displays the complete range of phases, similar to Venus and the Moon, as it moves in its inner orbit relative to Earth, which reoccurs over the so-called synodic period approximately every 116 days.

Mercury’s axis has the smallest tilt of any of the Solar System’s planets (about ​1⁄30 degree). Its orbital eccentricity is the largest of all known planets in the Solar System; at perihelion, Mercury’s distance from the Sun is only about two-thirds (or 66%) of its distance at aphelion.

Its orbital period around the Sun of 87.97 days is the shortest of all the planets in the Solar System.  A sidereal day (the period of rotation) lasts about 58.7 Earth days.

Mercury’s surface appears heavily cratered and is similar in appearance to the Moon’s, indicating that it has been geologically inactive for billions of years. Having almost no atmosphere to retain heat, it has surface temperatures that vary diurnally more than on any other planet in the Solar System, ranging from 100 K (−173 °C; −280 °F) at night to 700 K (427 °C; 800 °F) during the day across the equatorial regions. The polar regions are constantly below 180 K (−93 °C; −136 °F). The planet has no known natural satellites. 

Unlike many other planets which “self-heal” through natural geological processes, the surface of Mercury is covered in craters. These are caused by numerous encounters with asteroids and comets. Most Mercurian craters are named after famous writers and artists. Any crater larger than 250 kilometres in diameter is referred to as a Basin.

The largest known crater is Caloris Basin, with a diameter of 1,550 km. The impact that created the Caloris Basin was so powerful that it caused lava eruptions and left a concentric ring over 2 km tall surrounding the impact crater.

Two spacecraft have visited Mercury: Mariner 10 flew by in 1974 and 1975; and MESSENGER, launched in 2004, orbited Mercury over 4,000 times in four years before exhausting its fuel and crashing into the planet’s surface on April 30, 2015.

It is the smallest planet in the Solar System, with an equatorial radius of 2,439.7 kilometres (1,516.0 mi). Mercury is also smaller—albeit more massive—than the largestnatural satellites in the Solar System, Ganymede and Titan.  

As if Mercury isn’t small enough, it not only shrank in its past but is continuing to shrink today. The tiny planet is made up of a single continental plate over a cooling iron core. As the core cools, it solidifies, reducing the planet’s volume and causing it to shrink. The process crumpled the surface, creating lobe-shaped scarps or cliffs, some hundreds of miles long and soaring up to a mile high, as well as Mercury’s “Great Valley,” which at about 620 miles long, 250 miles wide and 2 miles deep (1,000 by 400 by 3.2 km) is larger than Arizona’s famous Grand Canyon and deeper than the Great Rift Valley in East Africa. 

The first telescopic observations of Mercury were made by Galileo in the early 17th century. Although he observed phases when he looked at Venus, his telescope was not powerful enough to see the phases of Mercury.

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images: Joseph Brimacombe, NASA/JPL, Wikimedia Commons

Solar System: 10 Things to Know This Week

January 8: Images for Your Computer or Phone Wallpaper

Need some fresh perspective? Here are 10 vision-stretching images for your computer desktop or phone wallpaper. These are all real pictures, sent recently by our planetary missions throughout the solar system. You’ll find more of our images at solarsystem.nasa.gov/galleries, images.nasa.gov and www.jpl.nasa.gov/spaceimages.

Applying Wallpaper: 1. Click on the screen resolution you would like to use. 2. Right-click on the image (control-click on a Mac) and select the option ‘Set the Background’ or 'Set as Wallpaper’ (or similar).

1. The Fault in Our Mars

This image from our Mars Reconnaissance Orbiter (MRO) of northern Meridiani Planum shows faults that have disrupted layered deposits. Some of the faults produced a clean break along the layers, displacing and offsetting individual beds.

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2. Jupiter Blues

Our Juno spacecraft captured this image when the spacecraft was only 11,747 miles (18,906 kilometers) from the tops of Jupiter’s clouds – that’s roughly as far as the distance between New York City and Perth, Australia. The color-enhanced image, which captures a cloud system in Jupiter’s northern hemisphere, was taken on Oct. 24, 2017, when Juno was at a latitude of 57.57 degrees (nearly three-fifths of the way from Jupiter’s equator to its north pole) and performing its ninth close flyby of the gas giant planet.

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3. A Farewell to Saturn

After more than 13 years at Saturn, and with its fate sealed, our Cassini spacecraft bid farewell to the Saturnian system by firing the shutters of its wide-angle camera and capturing this last, full mosaic of Saturn and its rings two days before the spacecraft’s dramatic plunge into the planet’s atmosphere on Sept. 15, 2017.

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4. All Aglow

Saturn’s moon Enceladus drifts before the rings, which glow brightly in the sunlight. Beneath its icy exterior shell, Enceladus hides a global ocean of liquid water. Just visible at the moon’s south pole (at bottom here) is the plume of water ice particles and other material that constantly spews from that ocean via fractures in the ice. The bright speck to the right of Enceladus is a distant star. This image was taken in visible light with the Cassini spacecraft narrow-angle camera on Nov. 6, 2011.

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5. Rare Encircling Filament

Our Solar Dynamics Observatory came across an oddity this week that the spacecraft has rarely observed before: a dark filament encircling an active region (Oct. 29-31, 2017). Solar filaments are clouds of charged particles that float above the Sun, tethered to it by magnetic forces. They are usually elongated and uneven strands. Only a handful of times before have we seen one shaped like a circle. (The black area to the left of the brighter active region is a coronal hole, a magnetically open region of the Sun).

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6. Jupiter’s Stunning Southern Hemisphere

See Jupiter’s southern hemisphere in beautiful detail in this image taken by our Juno spacecraft. The color-enhanced view captures one of the white ovals in the “String of Pearls,” one of eight massive rotating storms at 40 degrees south latitude on the gas giant planet. The image was taken on Oct. 24, 2017, as Juno performed its ninth close flyby of Jupiter. At the time the image was taken, the spacecraft was 20,577 miles (33,115 kilometers) from the tops of the clouds of the planet.

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7. Saturn’s Rings: View from Beneath

Our Cassini spacecraft obtained this panoramic view of Saturn’s rings on Sept. 9, 2017, just minutes after it passed through the ring plane. The view looks upward at the southern face of the rings from a vantage point above Saturn’s southern hemisphere.

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8. From Hot to Hottest

This sequence of images from our Solar Dynamics Observatory shows the Sun from its surface to its upper atmosphere all taken at about the same time (Oct. 27, 2017). The first shows the surface of the sun in filtered white light; the other seven images were taken in different wavelengths of extreme ultraviolet light. Note that each wavelength reveals somewhat different features. They are shown in order of temperature, from the first one at about 11,000 degrees Fahrenheit (6,000 degrees Celsius) on the surface, out to about 10 million degrees in the upper atmosphere. Yes, the sun’s outer atmosphere is much, much hotter than the surface. Scientists are getting closer to solving the processes that generate this phenomenon.

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9. High Resolution View of Ceres

This orthographic projection shows dwarf planet Ceres as seen by our Dawn spacecraft. The projection is centered on Occator Crater, home to the brightest area on Ceres. Occator is centered at 20 degrees north latitude, 239 degrees east longitude.

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10. In the Chasm

This image from our Mars Reconnaissance Orbiter shows a small portion of the floor of Coprates Chasma, a large trough within the Valles Marineris system of canyons. Although the exact sequence of events that formed Coprates Chasma is unknown, the ripples, mesas, and craters visible throughout the terrain point to a complex history involving multiple mechanisms of erosion and deposition. The main trough of Coprates Chasma ranges from 37 miles (60 kilometers) to 62 miles (100 kilometers) in width.

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Explore and learn more about our solar system at: solarsystem.nasa.gov/. 

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.

Belo arco circunzenital fotografado em 26 de Junho de 2016 no Texas. By www.eluniversohoy.net

Eu e minha tia triufamos no curral do Caprichoso! 🤩💙

Pequena galeria com imagens de colisão/fusão de galáxias, feitas pelo Telescópio Espacial Hubble.