Three weeks ago a new dust storm erupted on Mars. It’s the largest in 25 years and still growing. The storm is so big that amateur astronomers using modest telescopes can see it from Earth. And the cloud has raised the temperature of the frigid Martian atmosphere by a stunning 30 degrees Celsius. Now that’s global warming! Enjoying the best view of the storm is NASA’s Mars Global Surveyor in orbit around the Red Planet. The spacecraft carries an instrument called “TES” — short for Thermal Emission Spectrometer — that can measure the temperature and dust content of the Martian atmosphere on a daily basis.