Mortal as I am, I know that I am born for a day. But when I follow at my pleasure the serried multitude of the stars in their circular course, my feet no longer touch the earth - Ptolemy
This month there are two Full Moons. This is a rare event as the lunar cycle is 29.5 days long, so there's usually one Full Moon per calendar month, totalling 12 a year. The 2nd Full Moon of the same month means it's a 'Blue Moon' according to folklore, although some astronomers insist the explanation of two full moons in one calendar month dubs the second a 'Blue Moon' is a mistake perpetuated through common usage. But like the romantic-sounding supermoon, it seems the popular moniker has stuck and will continue to be referred to. Blue Moons don't happen every year, for example there wasn't a Blue Moon in 2014 and there won't be one in 2017. In 2018 there will be no Full Moon during February, which means, of course, that both January 2018 and March 2018 will be Blue Moon months.
The New Horizons spacecraft (launched in 2006) will have a close encounter with Pluto on 14 July. NASA scientists hope that there will be plenty of information garnered on the dwarf planet and its five moons.
July 2015 Diary Dates
- 01: Venus passes within half a degree of Jupiter
- 02: Full Moon - the Buck, Hay, Crane or Summer Moon
- 05: The Moon is at perigee (closest to Earth)
- 06: The Moon passes 3° north of Neptune
- 06: The Earth is at aphelion (furthest from the Sun)
- 07: The 18m-wide asteroid 2005 VN5 will pass Earth beyond the orbit of the Moon
- 07: The 73m-wide asteroid 2015 HM10 will pass Earth just beyond the orbit of the Moon (1.1 lunar distance)
- 09: The Moon passes within a degree of Uranus
- 12: The Moon passes 1° north of Aldebaran (alpha Tauri)
- 14: The New Horizons spacecraft will have a close encounter with Pluto
- 15: The 1.4km-wide asteroid 1994 AW1 will pass Earth beyond the orbit of the Moon
- 16: New Moon
- 18: The Moon passes 4° south of Jupiter
- 19: The Moon passes 0.4° south of Venus
- 19: The 565m-wide asteroid 2011 UW158 will pass Earth beyond the orbit of the Moon
- 20: The 38m-wide asteroid 2013 BQ18 will pass Earth beyond the orbit of the Moon
- 21: The Moon is at apogee (furthest from Earth)
- 23: Venus and Jupiter form a perfect triangle with Regulus (alpha Leonis)
- 25: The 1.6km-wide asteroid 1999 JD6 will pass Earth beyond the orbit of the Moon
- 26: The Moon passes 2° north of Saturn
- 30: Southern Delta Aquariid meteor shower peak
- 31: 2nd Full Moon of the month - now popularly known as a 'Blue Moon'
Chat about your celestial observances at the H2G2 Astronomy Society. Comment on anything in this edition of Babe Among the Stars by starting a new conversation below.