NOTES  ON SEPTEMBER 2017  NIGHT  SKY
by Eamon Henry; 9^th September 2017

This page, to be updated monthly, will let you know some things you can look out for in the night sky. The website http://www.jb.man.ac.uk/astronomy/nightsky  gives an available monthly outlook of present title “The Night Sky September 2017” compiled by Ian Morison and covering events throughout September. A complementary TV programme is the BBC programme “The Sky at Night” likely continuing on BBC Four sometime during the month.

The above website gives information about planets, eclipses, comets, galaxies, etc., some of which are of central interest for the month ahead. It also gives written comment on what to look for. I just offer a few extracts from this, in what follows. However, some of the comments are my own, e.g. planets’ or moons’ (satellites’) approximate distances. Please note that the planet shapes shown in this outlook do not necessarily coincide with what you get in a “here and now” view through a small telescope. This makes such “here and now” live viewing quite interesting.

Highlights of September 2017:

1. Jupiter: to be seen low in the southwestern sky after nightfall, at some 10 degrees above the horizon. Clear conditions should at any time make Jupiter’s four Galilean moons and the equatorial bands visible.   

2. Saturn: due southwest at its highest some 17 degrees above the horizon as darkness falls at the start of the month, with its ring-system open at some 26 degrees to our line of sight.

3. Mars: a morning object, not easily seen in the pre-dawn sky.

4. Mercury:  has become a morning object in direction east. Binoculars will be needed to observe it in the bright twilight.

5. Venus: rises in the east some 2 hours before sunrise, at the start of the month. During the month its visible lighted surface increases from some 84 to 91 percent of the half-sphere. On 16^th September in direction east, Venus , Mars and Mercury can be seen in an almost vertical line below to the left of the crescent Moon.

Phases of the Moon:  Full Moon 6^th September ;  Last Qr. 13^th;  New Moon 20^th;  1^st Qr. 28^th

Dublin Sunrise: 6.36am on 2^nd September; 6.48am on 9^th;7.00am on 16^th;7.13am on 23^rd;7.25am on 30^th     

Dublin Sunset: 8.12 pm on 2^nd September;7.55pm on 9^th;7.38pm on 16^th;7.21pm on 23^rd;7.04pm on 30^th

NOTE: the times given above are all in summertime, which began on 26^th March.