Category Science & Technology

Scientists discover lion species that roamed Australia 23 million years ago

Paleontologists have revealed a new species of marsupial lion in Australia. The now-extinct species, Lekaneleo roskellyae or Leo, once roamed the Riversleigh area in the north-west highlands of Queensland over 23 million years ago. It is one of the smallest lions ever discovered, and was about the size of a domestic cat.

Paleontologists from the University of New South Wales discovered the remains of the small lion at the Riversleigh World Heritage Area, where scientists have been finding fossils for decades.

Despite its small size, Leo would have been feared by other animals in the Riversleigh ancient rainforest. It had elongated, ‘bolt-cutting’ premolar teeth that were capable of easily slicing through the bones of its prey. This is the most extraordinary adaptation or evolution that a carnivorous mammal has ever developed anywhere in the world.

Marsupial lions died out 35,000 years ago, and are not closely related to modern lions that roam Africa or the endangered Asiatic lion in India.

 

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First-ever animal that doesn’t need oxygen to survive found

Scientists have discovered an animal that does not need oxygen to produce energy needed for its survival. The tiny, less than 10-celled parasite, Henneguya salminicola, lives in salmon muscle. As it evolved, the animal, a relative of jellyfish and corals, gave up breathing and consuming oxygen – or became anaerobic – to produce energy.

Mitochondria, a.k.a. the powerhouses of the cell, capture oxygen to make energy through aerobic respiration – but researchers found that H. salminicola lacks mitochondrial genes. Salmon muscle is a low-oxygen environment, making the ability to breathe oxygen useless to the organism. “Living in an oxygen-free environment, it has shed unnecessary genes responsible for aerobic respiration and became an even simpler organism,” said Prof. Dorothee Huchon from Tel Aviv University (TAU) in Israel. “Our discovery shows that evolution can go in strange directions. Aerobic respiration is a major source of energy, and yet we found an animal that gave up this critical pathway.”

 

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Earth captures new ‘mini moon’ the size of a car

Earth has acquired a second ‘mini-moon’ about the size of a car, according to astronomers who spotted the object circling our planet. The mass – roughly 6-11 feet in diameter – was observed by researchers Kacper Wierzchos and Teddy Pruyne at the NASA-funded Catalina Sky Survey in Arizona (U.S.).

This is the second asteroid known to orbit Earth. The only other asteroid, 2006 RHI20, rotated around Earth from September 2006 to June 2007.

The Smithsonian Astrophysical Observatory’s Minor Planet Center, which collects data on minor planets and asteroids, said “no link to a known artificial object has been found,” implying it was likely an asteroid captured by Earth’s gravity.

Earth’s new neighbor is not in a stable orbit around the planet and is unlikely to be around for very long. It is already heading away from the Earth-moon system, and was likely to escape in April.

 

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What are Asteroids?

ASTEROIDS

Asteroids are small, mostly rocky, irregular-shaped bodies. They are found orbiting the Sun in a band filling the 550-million-kilometre gap between Mars and Jupiter. The largest, Ceres, measures just under 1000 kilometres across, but only a handful have diameters greater than 100 kilometres. About 4000 have been recorded, but there are many thousands more too small to be identified.

Astronomers believe that, during the formation of the Solar System, Jupiter’s strong gravitational pull caused nearby planetesimals to smash into one another rather than build up into another planet. This left the belt of fragments we call the asteroids.

The asteroids have continued to collide with one another since their formation, producing smaller fragments called meteoroids. These have occasionally crashed on to Earth’s surface (when they are known as meteorites). It is feared that one day a large meteorite may devastate Earth, causing climatic change sufficient to wipe out many life-forms.

            Most asteroids are rocky, indicating they come from the outer layers of a former minor planet. But some are metallic – they come from the core of such a planet.

            A close-up view of the irregular shaped objects that make up the asteroid belt between Mars and Jupiter. From study of asteroid fragments that have fallen to Earth, scientists have dated the age of the Solar System to 4.6 million years ago.

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What are comets?

COMETS

Comets are potato-shaped lumps of dust measuring only a few kilometres across, but accompanied by (when near the Sun) tails of has or dust that stretch for hundreds of millions of kilometres across space. The lump of dust is fused together by frozen gases and water ice. Like all other objects in the Solar System, comets orbit the Sun, although their orbits are often very elliptical (elongated ovals), looping in towards the Sun from distant reaches of the Solar System. When a comet approaches the Sun, part of its ices melt and the gas and dust escape, forming a surrounding cloud, or coma. As it rounds the Sun, the coma is swept back into two tails, a straight gas tail and a broader, curved dust tail, always pointing away from the Sun.

Sometimes, small pieces of debris break off from comets. Great showers of these fragments, called meteors, sometimes come quite close to Earth. Millions of tiny particles burn up in Earth’s atmosphere. Commonly known as shooting stars, they appear to us as split-second streaks of light in the night sky.

FAMOUS COMETS

The English astronomer Edmund Halley (1656-1742) was the first to realise that comets were orbiting objects. He once made a famous prediction: a comet that he observed in 1682 would return to the skies in 1758. Halley believed that comets recorded in 1531 and 1607 were simply earlier sightings of the one he saw in 1682. Halley did not live to see his prediction come true. Halley’s Comet, as it has been known ever since, was duly sighted on Christmas Day 1758 and has reappeared every 75 to 76 years. When Halley’s Comet appeared in March 1986, the space probe Giotto flew within 600 kilometres of it, sending back pictures and sampling the gases and dust particles given off by it.

A sighting of a comet is always a great event. The 1997 appearance of Comet Hale-Bopp was the most spectacular of recent years. Comets can also be destructive if they pass too close to a planet. In July 1994, drawn in by gravity, fragments of Comet Shoemaker-Levy smashed into Jupiter, creating massive fireballs on impact.

            On 30th June 1908 there was a huge explosion in the Tunguska region of Siberia, Russia. Trees in an area about 100 km across were felled by the blast, but no crater was found. The Tunguska fireball may have been a comet exploding at an altitude of about 6 km.

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Do we have some more Moons also, other than Earth’s natural satellite?

MOONS

Moons, also known as satellites, are relatively small worlds that orbit the planets of the Solar System. Earth has one moon, known simply as the Moon, but other planets have many more – Saturn, for example, has at least 18 moons. Moons are very varied in size and form. Many have unusual landscape features that intrigue astronomers.

Moons are created in different ways. Some are the result of fragments of rock or ice being pulled together by gravity to form a globe. Others are asteroids that have been “captured” by a planet’s gravitational force.

All seven of the moons illustrated here larger than the smallest planet, Pluto, while the largest moons, Ganymede and Titan, are even bigger than Mercury, the second smallest planet. Jupiter’s four largest moons are all in the top seven. They are called the “Galileans” after the Italian scientist Galileo Galilei who first discovered them with one of the first telescopes in 1610. Ganymede has an icy surface with cratered plains and areas showing strange “grooved” patterns.

Titan, Saturn’s largest moon, is the only moon to have a thick atmosphere, made mainly of nitrogen. Beneath its continuous cloud layer, there may be a sea of methane.

Callisto, Jupiter’s second largest moon, is heavily cratered. Measuring 600 kilometres across, its most prominent crater, called Valhalla, is surrounded by a series of ripples. Io, the third of Jupiter’s Galileans, with its crust a vivid mixture of yellows, oranges, reds and blacks, looks a little like a pizza. In fact it is peppered with active volcanoes and lakes of molten rock.

Our own Moon is the fifth largest moon in the Solar System, although it would take 81 Moons to make up a world the size of Earth. The Moon’s lava plains indicate past volcanic activity, but there are no active volcanoes there today.

Next in order of size comes Europa, the fourth Galilean and an object of great interest amongst astronomers. Looking like a cracked egg, its surface consists of ice sheets that are continually melting and re-solidifying. It is by no means impossible that, beneath those ice sheets, there is a warm ocean of liquid water. Could it be that life has also evolved on Europa and that there are life-forms swimming in its oceans? Future space probe missions may find out.

Triton is Neptune’s largest moon. Its surface is the coldest place known in the Solar System. At -235°C, the temperature is low enough to freeze nitrogen. Triton was photographed in stunning detail by Voyager 2, the last of its close encounters, in 1989.

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