Category Astronomy

Halley is the only known short-period comet that is regularly visible to the naked eye from Earth, and the only naked-eye comet that can appear twice in a human lifetime. Halley last appeared in the inner parts of the Solar System in 1986 and will next appear in mid-2061.

Astronomy began changing swiftly around the time of Shakespeare, however. Many astronomers of his time held that Earth was the center of the solar system, but Nicolaus Copernicus — who died about 20 years before Shakespeare’s birth — published findings showing that the center was actually the sun.

It took several generations for Copernicus’ calculations to take hold in the astronomy community, but when they did, they provided a powerful model for how objects move around the solar system and the universe.

The comet appeared in 1531, 1607 and 1682. Halley suggested the same comet could return to Earth in 1758. Halley did not live long enough to see its return – he died in 1742 – but his discovery inspired others to name the comet after him.

On each successive journey to the inner solar system, astronomers on Earth turned their telescopes skyward to watch Halley’s approach.

The comet’s pass in 1910 was particularly spectacular, as the comet flew by about 13.9 million miles (22.4 million kilometers) from Earth, which is about one-fifteenth the distance between Earth and the sun. On that occasion, Halley’s Comet was captured on camera for the first time.

 

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Ceres is the earliest known and smallest of the current category of dwarf planets. Sicilian astronomer Giuseppe Piazzi discovered Ceres in 1801 based on the prediction that the gap between Mars and Jupiter contained a missing planet. It is only 590 miles (950 km) in diameter and has a mass of just 0.015 percent that of Earth.

In fact, Ceres is so small that it is classified as both a dwarf planet and an asteroid, and is often named in scientific literature as one of the largest asteroids in the solar system. Although it makes up approximately a fourth of the mass of the asteroid belt, it is still 14 less massive than Pluto.

NASA’s robotic Dawn mission arrived at Ceres in 2015. The mission has shown many interesting features on its surface, ranging from various bright spots to a 4-mile-high (6.5-kilometer-high) mountain. (Another mission, the European Space Agency’s Herschel Space Observatory, spotted evidence of water vapor in 2014.) 

 

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Known as “the hexagon”, this weather feature is an intense, six-sided jet stream at Saturn’s North Pole. Spanning some 30 000 km across, it hosts howling 320 km/h winds that spiral around a massive storm rotating anticlockwise at the heart of the region.

Saturn, with its multiple rings, is sometimes referred as “The jewel of the Solar System”. The hexagonal pattern at Saturn’s North Pole had been shrouded in mystery for a long time. Some believe it to be natural phenomena, while others thought it to be the result of some alien activity. The spacecraft Cassini’s dive into Saturn has given us a lot of photographs and information that comes very close to decoding this anomaly.

However, a team of scientists has created a new atmospheric model that suggests the storm is thousands of miles deep.

They tested the theory in a lab and think it deep roots could explain why the hexagon has been a feature on Saturn’s surface for so long.

The 3D model was created by scientists at Harvard University.

It’s based on previous storm hypotheses that claim jet streams in the gas giant planet’s atmosphere or within its pressurised mass could be responsible.

Using their 3D spherical shell model, the researchers found that deep rotating changes in temperature between gasses on the planet could be causing the storm to form in that shape.

 

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Van Allen radiation belt, doughnut-shaped zones of highly energetic charged particles trapped at high altitudes in the magnetic field of Earth. The zones were named for James A. Van Allen, the American physicist who discovered them in 1958, using data transmitted by the U.S. Explorer satellite.

Van Allen’s experiment on Explorer 1, which launched Jan. 31, 1958, had a simple cosmic ray experiment consisting of a Geiger counter (a device that detects radiation) and a tape recorder. Follow-up experiments on three other missions in 1958 — Explorer 3, Explorer 4 and Pioneer 3 — established that there were two belts of radiation circling the Earth.

While observations have continued for decades, our knowledge of the belts became more enhanced when the Van Allen Probes launched in 2012. They found that the belts were more complex than previously imagined. The probes showed that the shape of the belts depends on what particle is being studied. They also uncovered information hinting there is less radiation than imagined in certain parts of the Van Allen belts, which means spacecraft and humans would not need as much radiation protection if they are voyaging in that region.

 

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Created as surface ice vaporizes under the distant light of the Sun, Pluto’s atmosphere is predominantly nitrogen gas, along with small amounts of methane and carbon monoxide. Haze particles form high up in the atmosphere, more than 20 miles above the surface, as methane and other gases react to sunlight, before slowly raining down to the icy surface.

New Horizons found evidence of these particles when it sent back images showing a blue-tinted haze to Pluto’s atmosphere. Now, SOFIA’s data fills in even more details by discovering that the particles are extremely small, just 0.06-0.10 microns thick, or about 1,000 times smaller than the width of a human hair. Because of their small size, they scatter blue light more than other colors as they drift toward the surface, creating the blue tint.

With these new insights, scientists are reevaluating their predictions on the fate of Pluto’s atmosphere. Many forecasts indicated that as the dwarf planets moved away from the Sun, less surface ice would be vaporized — creating fewer atmospheric gases while losses to space continued — eventually leading to atmospheric collapse. But rather than collapsing, the atmosphere appears to change on a shorter cyclical pattern.

 

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The seventh planet from the Sun with the third largest diameter in our solar system, Uranus is very cold and windy. The ice giant is surrounded by 13 faint rings and 27 small moons as it rotates at a nearly 90-degree angle from the plane of its orbit. This unique tilt makes Uranus appear to spin on its side, orbiting the Sun like a rolling ball.

The first planet found with the aid of a telescope, Uranus was discovered in 1781 by astronomer William Herschel, although he originally thought it was either a comet or a star. 

Uranus took shape when the rest of the solar system formed about 4.5 billion years ago, when gravity pulled swirling gas and dust in to become this ice giant. Like its neighbor Neptune, Uranus likely formed closer to the Sun and moved to the outer solar system about 4 billion years ago, where it is the seventh planet from the Sun.

As an ice giant, Uranus doesn’t have a true surface. The planet is mostly swirling fluids. While a spacecraft would have nowhere to land on Uranus, it wouldn’t be able to fly through its atmosphere unscathed either. The extreme pressures and temperatures would destroy a metal spacecraft.

Uranus has 27 known moons. While most of the satellites orbiting other planets take their names from Greek or Roman mythology, Uranus’ moons are unique in being named for characters from the works of William Shakespeare and Alexander Pope.

All of Uranus’ inner moons appear to be roughly half water ice and half rock. The composition of the outer moons remains unknown, but they are likely captured asteroids.

 

Picture Credit : Google