Spacecraft and Instruments
As you have learned, the Sun affects the Earth and those of us living on Earth in many ways. We may already know a lot about the Sun but we are nowhere near having all the answers. SDO has three instruments on board to help us in our never ending quest to always know more. Hopefully, every new discovery we make will help us answer old questions and find answers to new questions.
SDO contains a suite of instruments that will provide observations leading to a more complete understanding of the solar dynamics that drive variability in the Earth's environment. This set of instruments will:
- 1. Measure the extreme ultraviolet spectral irradiance of the Sun at a rapid cadence
- 2. Measure the Doppler shifts due to oscillation velocities over the entire visible disk
- 3. Make high-resolution measurements of the longitudinal and vector magnetic field over the entire visible disk
- 4, Make images of the chromosphere and inner corona at several temperatures at a rapid cadence
- 5. Make those measurements over a significant portion of a solar cycle to capture the solar variations that may exist in different time periods of a solar cycle
Helioseismic and Magnetic Imager (HMI)
HMI looks at the outside of the Sun to try and determine what is happening on the inside.
Did you know that there are waves on the Sun? The Sun has billions of tiny ripples that are a little bit like shocks from an earthquake. They are caused by the Sun's convection zone. HMI will measure the ripples and the magnetic field on the visible surface of the Sun (the photosphere) using different colors or wavelengths. Since we can't actually go to the Sun to study it HMI will use color to measure the Sun's magnetic field. With all the information we gather using HMI about what is happening on the surface of the Sun, Scientists will be able to figure out what is going on inside and making all the cool stuff happen on the outside!
Atmospheric Imaging Assembly (AIA)
AIA will image the outer layer of the Sun's atmosphere, the corona, at all temperatures from 20 thousand to 20 million degrees. With high time resolution and a view that covers the entire visible hemisphere of the Sun, for the first time the evolution of all energetic solar events will be followed---from the original micro instabilities through the ejection of billions of tons of material into interplanetary space, to the bright flaring in the corona as the magnetic field is reconfigured in the biggest explosions in the solar system. Four telescope with two passbands each will provide eight full-Sun images every ten seconds, twenty four hours a day, seven days a week.
Extreme Ultraviolet Variablity Experiment(EVE)
EVE is made up of several small instruments. Again, we have nicknames for them: MEGS, ESP. EVE has to keep track of the extreme ultraviolet (EUV) rays that the Sun sends towards us. Ultraviolet (UV) rays are light, like any other light, but of colors that our eyes can't see. UV rays are what can cause skin cancer if we sit out in the Sun for too long over many years with no protection. Extreme ultraviolet rays are even more dangerous, but we on Earth are safe because EUV rays are completely absorbed high up in the Earth's atmosphere. The brightness of EUV light from the Sun changes when the magnetic field of the Sun is more active (like when the Sun spits particles and radiation towards Earth). Scientists want to have a better understanding of why and how the amount of EUV light from the Sun changes. It is EVE's job to help them figure it out. EVE is going to use color (different wavelengths), just like HMI and AIA, and will measure the amount of light in different EUV colors coming from the Sun. EVE will measure a spectrum every 10 seconds 24 hours a day! These measurements will help scientists predict the amount of EUV coming towards Earth at any time based on the activity of the Sun's magnetic field.