Spacewatch: Firing up for a close encounter with the sun

After lift-off, set for Saturday, Nasa's solar probe starts its six-year flight to within 3.8m miles of the sun - the nearest visit yet

Nasa's Parker Solar Probe is now on the launch pad at Cape Canaveral, Florida. Its launch window will open at 3.48am (eastern daylight time, or 7.48am Greenwich mean time) on Saturday 11 August. Protected by a sophisticated heat shield the probe is designed to go closer to the sun than any previous spacecraft.

The probe's mission is to dip into the solar atmosphere and deduce how the rarefied gasses there are heated to millions of degrees centigrade when the solar surface itself is just 6,000C.