Observing space weather

Global Ultraviolet Imager (GUVI) – Observing the space weather in Earth’s upper atmosphere.

About the Instrument

Instrument Type

The northern lights, or auroras, not only provide a fascinating and spectacular light show but also hint at a complex chemical and physical process taking place in the upper atmosphere (above 80 kilometers). Earth is subject to a variety of inputs from the Sun, but those taking place in the ionosphere, thermosphere and mesosphere have been particularly hard to observe and unravel. The APL-built TIMED mission, launched in 2001, continues to provide critical observations of this important region.

Imaging from Global Ultraviolet Imager
A global map of Earth's nightside ionosphere, made from a day's worth of images. The auroras stand out prominently near the poles, and ionospheric emissions in far-ultraviolet light are shown as bright, fluorescent green streaks crossing near the equator. These bright, equatorial ionospheric structures were made from a series of vertical swaths, each representing a single orbit of Earth.

Built by APL for the TIMED mission, the Global Ultraviolet Imager (GUVI) observes the upper atmospheric layers of Earth in the far-ultraviolet range. Over its nearly 20-year observation period, GUVI has provided insights into the chemistry and dynamics of the ionosphere and thermosphere. Understanding these processes provides useful information about the fundamental physics of the upper atmosphere as well as space weather and its effects on terrestrial applications such as radio communications and precise satellite orbit predictions.