For the second month in a row, it doesn’t truly get dark during July. For the sky to be completely dark, the Sun must get at least 18 degrees below the horizon and this only happens on the last 2 days of July from Ireland. Jupiter and Saturn are both prominent in the sky this month, rising earlier each evening. Again, this month you should keep an eye out for noctilucent clouds which can be seen some evenings shining in the north after sunset and before sunrise. I have another post about noctilucent clouds and the link is below:
https://thescienceshed.com/2020/05/29/noctilucent-clouds/
Sun and Moon
| Date | Sunrise (Irish Time) | Sunset (Irish Time) |
|---|---|---|
| 01/07/2021 | 05:01 | 21:55 |
| 15/07/2021 | 05:16 | 21:44 |
| 31/07/2021 | 05:39 | 21:21 |
| Moon Phase | Date |
|---|---|
| Third quarter | 01/07/2021 |
| New Moon | 10/07/2021 |
| First quarter | 17/07/2021 |
| Full Moon | 24/07/2021 |
Planets
Mercury
Mercury is hard to see as it is so close to the Sun. Make sure the Sun hasn’t risen before looking for it. This month, Mercury is a morning object, rising about 1 hour before sunrise at the start of the month. At the end of the month, it rises about 45 mins before the Sun. Look low in the North east before sunrise.
Venus
Venus is in the evening sky, low in the northwest for about 1.5 hours after sunset for most of the month.
Mars
Mars is very difficult to see this month as it is only seen in the evening twilight.
Jupiter
Jupiter is visible in the south east . It is very bright this month and rises just after midnight at the start of the month. By the month’s end, Jupiter rises just after 10pm.
Saturn
Saturn is also visible in the south this month. It rises at about 11.30pm at the start of the month and by the end of the month it rises about 9.30pm which means you won’t have to stay up too late to catch a view of it. Look low in the south.
Stars and Constellations
The above sky chart is for 23:00 on 15/07/2021. You can click on the chart to open a new tab and bring you to Heavens Above. On this website you can generate a custom chart for the time and date you wish. The spring constellations of Leo (the lion), Bootes (the herdsman) and Virgo (the virgin) still take prominence overhead early in the night. But they have now moved west slightly. An interesting fact about the constellation of Virgo is that the galaxy M87 is located in Virgo. M87 contains the supermassive black hole which astronomers managed to image the shadow of in 2019.
Look out for Cygnus (the swan), Lyra (the liar) and Aquila (the eagle). The brightest stars in these constellations are Deneb, Vega and Altair and they make up the Summer Triangle. By around midnight there are right overhead. Hercules (the hunter) is also overhead at this time of year.
In the south at this time of year is the constellation of Scorpius (the scorpion). This is the direction of the centre of our galaxy, the Milky Way. It never rises very high in the sky from Ireland, but if you look in the direction, from a dark location you should be able to make out that it is almost misty or milky with stars.
Over in the east you can see Pegasus (winged horse in Greek mythology), Andromeda (Princess of Ethiopia) and Perseus (the hero).
Paul Smith 