The waxing crescent6.6 day old moon
41.4 percent lit
10 July 2016
By Ade Ashford
It is now seven weeks (click here) since Mars was at opposition. The Red Planet presently shines at magnitude -1.1 and has a diameter of around 14.7 arcseconds. The Martian north pole is still tipped in our direction, but the planet’s shrinking, 90 percent illuminated disc now requires a telescopic magnification of about 125x to enlarge it to the same size as the Moon appears to the unaided eye.
By the middle of the month, the gulf between Earth and Mars will have grown to 60 million miles (96 million kilometres). The Red Planet has also resumed its prograde (west to east) motion against the stars of Libra, hence it’s drawing closer to Saturn as the weeks pass.
Magnitude +0.2 Saturn currently lies in the adjacent constellation of Ophiuchus, some 17 degrees (three-quarters of the span of an outstretched hand at arm’s length) to the left of Mars in mid-July. At this time Saturn lies 860 million miles (1,390 million kilometres) from Earth — in excess of 14 times further away than adjacent Mars.
Despite its great distance, Saturn’s globe still subtends almost 18 arcseconds, while the northern face of the glorious 42-arcsecond-wide ring system is tipped a very favourable 26 degrees toward Earth. Look for Saturn’s largest moon, Titan, a magnitude +8.7 ‘star’ four ring diameters west of the planet on 19 July....
