With the Hubble Space Telescope (HST) placed 353 miles (569 km) above the surface of Earth, astronomers have worked around this problem. The telescope is above the obstructing atmosphere of the Earth. Taking images now can be done without any background light with all available wavelengths open for viewing.
The space telescope is named after famed astronomer, Edwin Hubble. Hubble is the astronomer credited with the theory of the expanding universe.
HST's images are extremely sharp and detailed. Hubble's Ultra-Deep Field image, for example, is the most detailed visible light image ever made of the universe's far distant objects. Many of the Hubble Space Telescope's images and observations have led to breakthroughs and advancements in astrophysics, such as accurately determining the rate of expansion of the universe.
The HST was built by the National Aeronautics and Space Administration (NASA), with contributions from the European Space Agency (ESA), and is operated by the Space Telescope Science Institute.
Dramatic change spotted on a faraway planet
Astronomer Alain Lecavelier des Etangs (CNRS-UPMC, France) and his team used Hubble to observe the atmosphere of exoplanet HD 189733b[1] during two periods in early 2010 and late 2011, as it was silhouetted against its parent star[2]. While backlit in this way, the planet’s atmosphere imprints its chemical signature on the starlight, allowing astronomers to decode what is happening on scales that are too tiny to image directly. The observations were carried out in order to confirm what the team had previously seen once before in a different planetary system: the evaporation of an exoplanet’s atmosphere.
HD 189733b has a blue sky, but that’s where the similarities with Earth stop. The planet is a huge gas giant similar to Jupiter, but it lies extremely close to its star, just one thirtieth the distance Earth is from the Sun. Even though its star is slightly smaller and cooler than the Sun, this makes the planet’s climate exceptionally hot, at above 1000 degrees Celsius, and the upper atmosphere is battered by energetic extreme-ultraviolet and X-ray radiation. As such, it is an excellent candidate to study the effects of a star on a planetary atmosphere.
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| Astronomers using the NASA/ESA Hubble Space Telescope have seen dramatic changes in the upper atmosphere of a faraway planet. Just after a violent flare on its parent star bathed it in intense X-ray radiation, the planet’s atmosphere gave off a powerful burst of evaporation. The observations give a tantalising glimpse of the changing climates and weather on planets outside our Solar System. |
“The first set of observations were actually disappointing,” Lecavelier says, “since they showed no trace of the planet’s atmosphere at all. We only realised we had chanced upon something more interesting when the second set of observations came in.”
The team’s follow-up observations, made in 2011, showed a dramatic change, with clear signs of a plume of gas being blown from the planet at a rate of at least 1000 tonnes per second. “We hadn’t just confirmed that some planets’ atmospheres evaporate,” Lecavelier explains, “we had watched the physical conditions in the evaporating atmosphere vary over time. Nobody had done that before.”
