General, Research, Technology

What is outside the solar system?

Space probes Voyager 1 and Voyager 2allowed humanity to get acquainted with the solar system. Until the launch of the spacecraft in 1977, we knew practically nothing about most of the planets in our galactic home. As he writes in his book “Blue Dot. The cosmic future of mankind "astronomer and popularizer of science Carl Sagan," these devices told us about the wonders of other worlds, about the uniqueness and fragility of ours, about births and sunsets. They opened up to us the distant corners of the solar system. It was they who investigated the bodies, which may become the homeland of our distant descendants. " Today, 43 years later, Voyagers are still roaming space and sending data to Earth about their surroundings - the mysterious, dark interstellar space. As the first man-made objects to leave our solar system, Voyagers are at risk of invading uncharted territory, billions of kilometers from home. No other spacecraft has ever swam so far into the cosmic ocean.

Hidden outside our star's sphere of influence is a cold, mysterious interstellar space

If we consider the distance at which our star can no longer hold any bodies in orbits as the limit of the solar system, then the Voyagers will spend tens of thousands of years in it.

Astronomer, astrophysicist, popularizer of science Carl Sagan ("Blue dot. The cosmic future of mankind").

What is interstellar space?

Far from the protective embrace of the Sun, the edge of the Sunsystems seem like a cold, empty and lifeless place. Unsurprisingly, the gaping space between us and nearby stars seemed for a long time a frighteningly vast space of nothingness. Until recently, it was a place where humanity could only look from afar.

Astronomers devoted only to interstellar spacefleeting attention, preferring instead to focus telescopes' attention on the luminous masses of nearby stars, galaxies and nebulae. Meanwhile, both Voyagers are still sending data to Earth from this strange region we call interstellar space.

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Over the past century, scientists have been buildinga picture of what the interstellar medium is made of, largely thanks to observations with radio and X-ray telescopes. They found that interstellar space is composed of highly diffuse ionized hydrogen atoms, dust and cosmic rays, punctuated by dense molecular clouds of gas that are believed to be the birthplace of new stars.

But its exact nature is directly behindoutside our solar system has been largely a mystery, mainly because the sun, all planets and the Kuiper belt are contained within a giant protective bubble formed by the solar wind known as heliosphere.

As the Sun and its surrounding planets sweep through the galaxy, this bubble hits the interstellar medium like an invisible shield, trapping most of the harmful cosmic rays and other materials.

The size and shape of the heliospheric bubble changes as it passes through different regions of the interstellar medium. The image shows the location of the spacecraft Voyager 1 and Voyager 2.

But its life-saving properties also make it difficultthe study of what lies beyond the heliosphere. That is why, according to some scientists, the only way to get an idea of ​​interstellar space is to fly away from the Sun, look back and get an image from outside the heliosphere. But this is no easy task - compared to the entire Milky Way galaxy, our solar system looks smaller than a grain of rice floating in the middle of the Pacific Ocean. Yet Voyagers are far from the outer edge of the heliosphere.

Read more interesting articles about the secrets of the solar system discovered by robotic probes "Voyager" on our channel in Yandex.Zen. There are regularly published articles that are not on the site.

The heliosphere and the solar wind

The heliosphere, as scientists have found, unexpectedlyis large, which suggests that the interstellar medium in this part of the galaxy is less dense than previously thought. The sun cuts a path through interstellar space like a ship moving through water, creating a "bow wave" and trailing a trail behind it, possibly with tail (or tails) in a comet-like shape. Both Voyagers passed through the "nose" of the heliosphere, and therefore did not provide any information about the tail.

"According to Voyager estimates, the heliopause has a thicknessabout one astronomical unit (149,668,992 kilometers, which is the average distance between the Earth and the Sun). It is not really a surface. This is a region with complex processes. And we don't know what's going on there, ”Jamie Rankin, a researcher at Princeton University, told

By the solar wind researchers call the flow of ionizedparticles emanating from the solar crust (at a speed of 300-1200 km / s) into the surrounding space. The solar wind is one of the main components of the interplanetary medium.

So, in the artist's view, looks like a solar storm that hit Mars.

And although bursts of solar wind mayto provide scientists with interesting data on what is happening in interstellar space, it appears to have surprisingly little effect on the overall size and shape of the heliosphere.

It turns out that what happens outside the heliosphere matters much more than what happens inside it.

The solar wind can increase or decrease withover time without significantly affecting the bubble. But if this bubble moves to a region of the galaxy with a denser or less dense interstellar wind, it will begin to shrink or grow. Well, we hope that Voyagers will send data to Earth about their surroundings for a long time to come, and we will finally learn more about what exactly is happening in this mysterious interstellar space.