Why do we launch telescopes into space?

Herschel and Aquila
Credit: ESA/SPIRE & PACS Consortia/Ph. André (CEA Saclay)/Gould’s Belt Key Programme Consortia

The Earth’s atmosphere blurs our view of the cosmos. It also blocks certain types of radiation. For an unobstructed view, you need to be above the atmosphere. That’s why we launch telescopes into space.

Spitzer Space Telescope
Hot view: High above Earth’s atmosphere, NASA’s Spitzer Space Telescope studies the Universe at infrared wavelengths.
Credit: NASA/JPL-Caltech/R. Hurt (SSC)
Sunbathing SOHO
Sunbathing: The Solar and Heliospheric Observatory (SOHO) is a NASA/ESA space telescope designed to observe our star, the Sun.
Credit: SOHO (ESA/NASA)

Even on a cloudless night, we have to look through our atmosphere to observe the Universe. Turbulence in the air causes stars to twinkle. This makes it impossible to study very fine details. Moreover, many types of electromagnetic radiation from space are blocked by the atmosphere: gamma rays, X-rays, ultraviolet radiation and large portions of the infrared and submillimetre spectrum cannot be observed from the ground. Therefore, ever since the dawn of the space age, telescopes have been put on board rockets and satellites.

Gaia
Milky Way mapper: With its ultra-precise instruments, ESA’s Gaia space telescope is mapping the Milky Way in unprecedented detail.
Credit: ESA–D. Ducros
EUCLID
Cosmology champion: To be launched in 2020, Euclid will shed light on the expansion history of the Universe and the role of dark matter and dark energy.
Credit: ESA/C. Carreau

Space telescopes don’t have to deal with twinkling stars and they can see light that is blocked by the Earth’s atmosphere. However, they are expensive and difficult to build.