Scientists call the region of space influenced by the sun the heliosphere – but without an interstellar probe, they don’t know much about its shape

This article was originally published on conversation. This publication is a feature of Space.com Expert Voices: Commentary and Insights.

Sarah Spitzer He is a research associate at the University of Michigan’s School of Climate and Space Science and Engineering.

The sun heats the earth and creates an environment where humans and animals can live, but that’s not all it does: it also affects the wider universe. Heliospherearea of space Influenced by the sun, Over 100 times larger than the distance from the sun to the earth Earth.

The Sun is a star that constantly emits plasma (high-energy ionized gas) called the solar wind. Constant solar windThe Sun occasionally emits eruptions of plasma. Coronal mass ejectioncan contribute to Auroraand an explosion of light and energy, It’s called a flare.

The plasma emitted from the sun is magnetic fieldThey come together Heliosphere The surrounding local interstellar medium – the plasma, neutral particles, dust, etc. that fills the space between the stars. Performer and their respective celestial spheres. Solar physicists like me I want to understand the heliosphere and how it interacts with interstellar matter.

The eight planets known to Earth are Solar System, Asteroid belt while Mars and Jupiterand the Kuiper Belt – A belt of bodies beyond Neptune that contains asteroids Pluto Everything exists within the heliosphere, which is so large that objects in the Kuiper Belt orbit the Sun closer to it than it does. The nearest boundary of the heliosphere.

An artist’s depiction of the heliosphere and its place in the local interstellar medium and the Milky Way galaxy. Interstellar probes will travel farther than any spacecraft to date and could help scientists get a better look at the heliosphere (the sun’s influence in space) from the outside. (Image courtesy of JHU/APL)

Heliospheric Protection

When a distant star explodes, Emits large amounts of radiation Emitted into interstellar space in the form of high-energy particles known as cosmic raysThese cosmic rays are dangerous to living organisms and can damage electronic equipment and spacecraft.

The Earth’s atmosphere protects life on Earth It is protected from the effects of cosmic radiation, but even before that, the heliosphere itself acts as a cosmic shield against most interstellar radiation.

In addition to cosmic radiation, neutral particles and dust are steadily streaming into the heliosphere from the local interstellar medium. These particles are Affect the space around the Earth And it may change How the solar wind reaches Earth.

Supernovae and interstellar matter may also have played a role Origin of life and Human evolution Some researchers predict that on Earth, the heliosphere came into contact with a cold, dense particle cloud of interstellar matter millions of years ago. Caused the shrinking of the heliosphereThis would expose the Earth to localized interstellar matter.

Unknown shape

However, scientists don’t actually know what the heliosphere is shaped like. The shapes of the models are diverse. From spherical to comet-shaped to croissant-shaped. These predictions vary Its size is hundreds to thousands of times its distance. Sun To Earth.

However, scientists define the direction in which the Sun is moving as the “nose” direction, and the opposite direction as the “tail” direction. The nose direction should be the shortest distance to the heliopause, the boundary between the heliosphere and the local interstellar medium.

NASA's Voyager 2 spacecraft entered interstellar space in November 2018, more than six years after its twin, Voyager 1. Data from Voyager 2 helped shed more light on the structure of the heliosphere, the giant bubble that the sun blows around itself.

An artist’s depiction of the heliosphere. Its actual shape is unknown. Examples of the Sun, the heliopause, the leading and trailing directions, and the flank directions have been added to the label. The Voyager spacecraft are thought to have left the heliosphere during their decades-long journey. (Image courtesy of NASA/JPL-Caltech)

Until now, no spacecraft has been able to get a good look at the outer heliosphere or properly sample the local interstellar medium, which could allow scientists to learn more about the shape of the heliosphere and its interactions with the local interstellar medium, the outer space environment.

Voyager crosses the heliopause

In 1977, NASA Voyager missions: Two spacecraft pass Jupiter, Saturn, Uranus and Neptune These objects are located on the outer edge of the solar system. Scientists have observed these objects and found that: Gas giantsThe spacecraft will pass through the heliopause separately, Interstellar space In 2012 and 2018 respectively.

meanwhile Voyager 1 The two are the only spacecraft that may have passed through the heliopause and are well beyond their original mission lifetimes. No longer returning the data I need This is because equipment will slowly break down or lose power.

These spacecraft were designed to study planets, not interstellar matter, which means they don’t have the right instruments on board to make all the measurements of the interstellar matter or heliosphere that scientists need.

This is where potential interstellar missions could come in: A spacecraft designed to fly beyond the heliopause could help scientists understand the heliosphere by observing it from its outer reaches.

Interstellar probe

The heliosphere is so large that It will take probes decades to reach the boundary.Flat Use Gravity Assist From a giant planet like Jupiter.

The Voyager spacecraft will no longer be able to provide data from interstellar space long before the probes leave the heliosphere, and after they are launched, it will take about 50 years or more, depending on their orbit, to reach the interstellar medium. National Aeronautics and Space Administration (NASA) The longer we wait to launch a probe, the less time scientists will have to carry out missions in the outer heliosphere and local interstellar medium.

NASA, Interstellar probeThe probe will measure plasma and magnetic fields in the interstellar medium and photograph the heliosphere from the outside. In preparation, NASA asked more than 1,000 scientists for input on the mission concept.

First report They recommended that the probe follow an orbit about 45 degrees away from the tip of the heliosphere, which would retrace part of the Voyager path but reach new areas of space, allowing scientists to study new areas and revisit partially known parts of the universe.

This route will give the probe only a partial view of the heliosphere, meaning it will miss out on the heliotail, the region scientists know least about.

Scientists believe that the plasma that makes up the heliosphere is mix Plasma that makes up interstellar matter. This is Magnetic reconnectionThis allows charged particles to flow from the local interstellar medium into the heliosphere, and just like the neutral particles coming in through our nose, these particles affect the space environment within the heliosphere.

But in this case, the particles have an electric charge and can interact with the magnetic fields of the Sun and planets. These interactions occur at the boundaries of the heliosphere, very far from Earth, but affect the internal structure of the heliosphere.

in New Research In a paper published in Frontiers in Astronomy and Space Sciences, my colleagues and I evaluated six possible launch orientations, from tip to tail, and found that an orbit that cuts across the side of the heliosphere toward the tail provides the best picture of the heliosphere’s shape, rather than one closer to the tip.

An orbit along this line will give scientists a unique opportunity to study an entirely new region of space within the heliosphere: once the probe leaves the heliosphere and enters interstellar space, it will be able to view the heliosphere from the outside at an angle, giving scientists more detailed information about its shape, especially its controversial tail region.

Ultimately, no matter which direction an interstellar probe is launched in, the science it would provide would be invaluable, and quite literally astronomical.

Global News

Scientists call the region of space influenced by the sun the heliosphere – but without an interstellar probe, they don’t know much about its shape

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