The Sun


The sun is a dynamic star.

Why Parker Solar Probe?

We live in the sun's atmosphere! This mission will provide insight on a critical link in the Sun-Earth connection. Data will be key to understanding and, perhaps, forecasting space weather.

We need to go so close because:

  • the corona is unstable, producing the solar wind, flares and coronal mass ejections – we need to study at the source!
  • millions of tons of highly magnetized material can erupt from the sun at speeds of several million miles an hour – fast enough to get from Washington to LA in seconds!

Why is the corona hotter than the surface? Why is there a solar wind?

We can only answer these questions by getting up close and personal with our star

Two views of the sun's atmosphere

The concept for a "Solar Probe" dates back to "Simpson's Committee" of the Space Science Board (National Academy of Sciences, 24 October 1958).

The need for extraordinary knowledge of sun from remote observations, theory, and modeling to answer the questions:

  • Why is the solar corona so much hotter than the photosphere?
  • How is the solar wind accelerated?

The answers to these questions have been of top priority in multiple Roadmaps and Decadal Surveys.

We live in the atmosphere of the sun.

Physics of the corona and inner heliosphere connect the activity of the sun to the environment and technological infrastructure of Earth will:

  • drive the fundamental physics of the heliosphere, aurora, and magnetosphere of Earth and other planets
  • help us improve satellite communications, power grid issues, pipeline erosion, radiation exposure on airline flights, astronaut safety

Until we can explain what is going on up close to the sun, we will not be able to accurately predict space weather effects that can cause havoc at Earth.

The SunSun-Earth Connections

From there to here...Billions of tons of solar material are hurled from the sun at millions of miles an hour. When the material reaches Earth it interacts with our protective magnetic field.

Earth's Magnetosphere

Dangerous electron and protons are not able to penetrate down to Earth's surface but are forced to move around it by the magnetic field.

Earth responds to the changing sun - this response is known as Space Weather.

Image of an aurora
Diagram of the sun's magnetic field

The Aurora is a physical sign of this Space Weather.

  • The corona is unstable, producing the solar wind, flares and coronal mass ejections
  • Billions of tons of highly magnetized material can erupt from the sun at speeds of several million miles an hour
  • Washington to LA in seconds!!

Why do we study the solar wind and the sun?

  • The sun is a source of light and heat for life on Earth.
  • Scientists want to understand how it works, why it changes, and how these changes influence us here on planet Earth.
  • The sun is the source of the solar wind; a flow of gases from the sun that streams past Earth at speeds of more than 500 km per second (a million miles per hour).
  • Disturbances in the solar wind shake Earth's magnetic field and pump energy into the radiation belts.
  • This "Space Weather" can change the orbits of satellites and shorten their lifetimes.
  • We are now incredibly dependent upon satellites in space and need to be able to predict space weather.
  • Shaking Earth's magnetic field can also cause surges in power lines that destroy equipment and knock out power over large areas.
  • Until we can explain what is going on up close to the sun, we will not be able to accurately predict space weather effects that can cause havoc at Earth

The SunThe Corona

Parker Solar Probe provides:

  • Statistical survey of outer corona
  • 1st perihelion (0.16 AU 0r ~15 million miles) 3 months after launch
  • Closest approach below 10 Rs (0.04 AU or 4 million miles)
  • Excellent sampling of all types of solar wind
    • Measurements from within the region where all the action happens
    • Particle measurements from the lowest energy plasma through the most energetic particles associated with solar flares
    • Measurements of plasma waves that enable energy &momentum flow
    • Coronal imaging "from the inside out" bridges local to global scales by providing the context