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Q: Why the Focus on Digital Media than physical marketing?

2 weeks 19 hours ago in  Web & Technology - Other cities

 
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Minor Official

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Why not?

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2 weeks 5 hours ago
 
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No, why!

 

 

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2 weeks 15 hours ago
 
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Why not?

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 'cause ... I just came back from ... 

 

https://www.bbc.com/future/article/20200908-the-weird-space-that-lies-ou...

 

The weird space that lies outside our Solar System

 

The mysterious dark vacuum of interstellar space is finally being revealed by two intrepid spacecraft that have become the first human-made objects to leave our Solar System.

 

Far from the protective embrace of the Sun, the edge of our Solar System would seem to be a cold, empty, and dark place. The yawning space between us and the nearest stars was for a long time thought to be a frighteningly vast expanse of nothingness.

Until recently, it was somewhere that humankind could only peer into from afar. Astronomers paid it only passing attention, preferring instead to focus their telescopes on the glowing masses of our neighbouring stars, galaxies and nebula.

But two spacecraft, built and launched in 1970s, have for the past few years been beaming back our first glimpses from this strange region we call interstellar space. As the first man-made objects to leave our Solar System, they are venturing into uncharted territory, billions of miles from home. No other spacecraft have travelled as far.

 

And they have revealed that beyond the boundaries of our solar system lies an invisible region of chaotic, frothing activity.

“When you look at different parts of the electromagnetic spectrum, that area of space is very different from the blackness we perceive with our eyes,” says Michelle Bannister, an astronomer at the University of Canterbury in Christchurch, New Zealand, who studies the outer reaches of the Solar System. “Magnetic fields are fighting and pushing and tied up with each other. The image you should have is like the plunge pool under Niagara Falls.”

Instead of tumbling water, however, the turbulence is the result of the solar wind a constant, powerful stream of charged particles, or plasma, spraying out in every direction from the Sun – as it crashes into a cocktail of gas, dust, and cosmic rays that blows between star systems, known as the “interstellar medium”.

Scientists have been building up a picture of what the interstellar medium is made of over the past century, thanks largely to observations with radio and X-ray telescopes. They have revealed it is composed of extremely diffuse ionised hydrogen atoms, dust, and cosmic rays interspersed with dense molecular clouds of gas thought to be the birthplace of new stars.

But its exact nature just outside our solar system has been largely a mystery, principally because the Sun, all eight planets and a distant disc of debris known as the Kuiper Belt, are all contained within a giant protective bubble formed by the solar wind, known as the heliosphere. As the Sun and its surrounding planets hurtle through the galaxy, this bubble buffets against the interstellar medium like an invisible shield, keeping out the majority of harmful cosmic rays and other material.

But its life-saving properties also make it more difficult to study what lies beyond the bubble. Even determining its size and shape is difficult from within.

“It's like you're inside your home and you want to know what it looks like. You have to go outside and take a look to really tell,” says Elena Provornikova, a postdoctoral researcher at the Johns Hopkins University Applied Physics Laboratory. “The only way to get an idea is to travel far away from the Sun, look back, and take an image from outside the heliosphere.”

This is no simple task. Compared to the whole of the Milky Way, our Solar System looks smaller than a grain of rice floating in the middle of the Pacific. And yet, the outer edge of the heliosphere is still so distant that it took more than 40 years for the Voyager 1 and Voyager 2 spacecraft to reach it as they flew from Earth.

Voyager 1, which took a more direct route through the Solar System, passed out into interstellar space in 2012, before Voyager 2 joined it in 2018. Currently around 13 billion and 11 billion miles from Earth respectively, they are now drifting out, ever further into the space beyond our Solar System, sending back more data as they do.

What these two aging probes revealed about the boundary between the heliosphere and the interstellar medium has provided fresh clues about how our Solar System formed, and how life on Earth is even possible. Far from being a distinct boundary, the very edge of our Solar System actually churns with roiling magnetic fields, clashing stellar windstorms storms of high energy particles and swirling radiation.

The size and shape of the heliosphere bubble alters as the Sun’s output changes, and as we pass through different regions of the interstellar medium. When the solar wind rises or falls, it changes the outward pressure on the bubble.

In 2014, the Sun’s activity surged, sending what amounted to a solar-wind hurricane sweeping out into space. The blast quickly washed over Mercury and Venus at close to 800 km per second (497 miles per second). After two days and 150 million km (93.2 million miles), it enveloped Earth. Fortunately, our planet’s magnetic field shielded us from its powerful, damaging radiation.

The gust pushed past Mars a day later and carried on through the asteroid belt toward the distant gas giants Jupiter, Saturn, Uranus and after more than two months, Neptune, which orbits nearly 4.5 billion km (2.8 billion miles) from the Sun.

After more than six months, the wind finally reached a point more than 13 billion km (8.1 billion miles) from the Sun known as the “termination shock”. Here, the Sun’s magnetic field, which propels the solar wind, becomes weak enough for interstellar medium to push against it.

The solar wind gust emerged from the termination shock traveling at less than half its previous speed the hurricane downgraded to a tropical storm. Then in late 2015, it overtook the irregularly shaped form of Voyager 2, which is about the size of a small car. The plasma surge was detected by Voyager’s 40-year-old sensing technologies, powered by a slowly decaying plutonium battery.

The probe beamed data back toward Earth, which even at the speed of light took 18 hours to reach us. Astronomers could only receive Voyager’s information thanks to a massive array of 70-metre satellite dishes and advanced technology that hadn’t been imagined, let alone invented, when the probe left Earth in 1977.

The solar wind surge reached Voyager 2 while it was still just inside our Solar System. A little more than a year later, the last gasps of the dying wind reached Voyager 1, which had crossed over into interstellar space in 2012.

The different routes taken by the two probes meant one was about 30 degrees above the solar plane, the other the same amount below. The solar wind burst reached them in different regions at different times, which provided useful clues about the nature of the heliopause.

The data revealed that the turbulent boundary s millions of kilometres thick. It covers billions of square kilometres around the surface of the heliosphere.

The heliosphere is also unexpectedly large, which suggests that the interstellar medium in this part of the galaxy is less dense than people thought. The Sun cuts a path through interstellar space like a boat moving through water, creating a “bow wave” and stretching a wake out behind it, possibly with a tail (or tails) in shapes similar to those of comets. Both Voyagers exited through the “nose” of the heliosphere, and so provided no information about the tail.

The estimate from the Voyagers is that the heliopause is about one astronomical unit thick (93 million miles, which is the average distance between the Earth and the Sun),” says Provornikova. “It's not really a surface. It's a region with complex processes. And we don’t know what’s going on there.

 

”... there's more ... of the outer space ..

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1 week 6 days ago
 
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Ours is not to question why...

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1 week 6 days ago
 
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A: Going to HK would be the best bet I reckon, especially if you were loo
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