Free Astronomy Magazine September-October 2015

SEPTEMBER-OCTOBER 2015 On 14 July, at 7:49 a.m. EDT (USA Eastern Daylight Time), New Horizons, at a speed of 49,600 km/h, passes one minute earlier than scheduled the point of closest approach point to Pluto, just 12,470 km from its surface (less than Earth’s di- ameter). In the hours just before and after that mo- ment, the space- craft devotes all its energies to the seven scientific in- struments fitted aboard, which col- lect such an amount of data that it will take a full 16 months to trans- fer it all back to us, i.e. un- til November 2016! While New Horizons reaches the highlight A bove, a pro- visional map of Pluto. Left, the planet viewed in enhanced colour to highlight areas with different chemical-miner- alogical surface composition. The diagram in the next page shows the gas tail ex- tending from Pluto under the pressure of the solar wind. [NASA/ Johns Hopkins Univer- sity Applied Phy- sics Laboratory/ Southwest Re- search Institute]