Weymouth Astronomy

The Planets - July 2018

Observing the planets can be extremely rewarding. Everyone remembers the first time they observed Saturn and it's rings or the gas giant Jupiter and it's Galillean Moons. Solar System


Mercury, the innermost planet shining at around zero magnitude early in the month reaches greatest elongation west of the Sun on July 12th. It will be then be seen about 15 degrees down to the lower right of Venus but will have dimmed to magnitude +1 by the 17th before fading rom view into the Sun's glare.


Venus can be seen low in the west after nightfall sinking towards the horizon as the month progresses. On July 9th Venus is close to Regulus in Leo and on the 15th near to a waxing crescent Moon.


Mars currently in Capricornus is moving in retrograde motion westwards as it moves towards its closest approach to Earth since 2003 on the night of July 30th/31st. Mars begins the month rising about 2 hours after sunset shining at magnitude -2.2 but its brightness peaks at -2.8 during the final week of July.


Jupiter can be seen due south soon after sunset at the start of the month and over towards the southwest as the month progresses. Jupiter's equatorial bands and sometimes the Great Red Spot and up to four of its Gallilean moons will be visible in a small telescope. Moving slowly westwards in Libra during the month, Jupiter is heading towards the southern part of the ecliptic and will only have an elevation of 20 degrees when crossing the meridian.


Saturn was at opposition on the 27th of June and will be visible during the (few) hours of darkness. It will be highest in the south around midnight as July begins and a little earlier by month's end. Lying in Sagittarius the 'ringed planet' is close to the topmost star of the 'teapot' slowly moving in retrograde to within a few degrees of M8, the Lagoon Nebula, and M20, the Trifid Nebula.

Information collated from Jodrell Bank and Astronomy Now magazine