Summer has fully arrived, bringing hot days and short, warm nights. July is undoubtedly the month when the Milky Way dominates the sky, stretching across in a broad band. Mid-summer in our latitudes is the best time to observe the constellation Sagittarius, which points to the center of our Galaxy, offering astronomy enthusiasts many interesting objects for both photography and visual observation.
Two celestial birds (Cygnus and Aquila) and an ancient musical instrument (Lyra) are the “homes” of three bright stars. Deneb, Altair, and Vega are located in these constellations, forming a remarkable asterism, the Summer Triangle.
The maximum of the Delta Aquariids meteor shower will mark the end of the month. However, its radiant in our latitudes remains quite low, so we should not expect particularly high activity.
Of the bright planets, only Mars and Mercury will be visible in the evening sky low above the western horizon, while Venus and Saturn are available for observations before dawn. At the end of June, Jupiter’s conjunction with the Sun took place – the planet passed exactly behind our central star. Now the conditions for observing the gas giant will gradually improve, and at the end of July it will also be possible to see it in the pre-dawn sky low above the horizon.
Another interesting celestial phenomenon to look out for this month, especially in the northern regions (latitudes 55°-65°), is noctilucent clouds. Suspended high in the atmosphere, about 80 km above the surface, ice crystals reflect light from the Sun, which is 6°-16° below the horizon, creating a spectacular “light veil” low in the twilight sky.
Source: Astrobin.
List of events
👀 🔭 📷 July 3 – Earth passes the aphelion, the farthest point of its orbit from the Sun.
👀 🔭 📷 July 4 – the conjunction of Venus (-4.1m) and Uranus (+5.8m), observed before dawn in the constellation Taurus, near the Pleiades. The angular distance between the planets will be 2.3°.
👀 🔭 📷 July 4 – Mercury is at its greatest eastern elongation, seen low over the western horizon shortly after sunset.
👀 🔭 📷 July 6 – the conjunction of Saturn (+0.9m) and Neptune (+7.9m) in the pre-dawn sky in the constellation Pisces, with only 58′ separating the planets – a little less than a degree.
👀 🔭 📷 July 10 – full moon, exact time 8:37 p.m. GMT (3:37 p.m. EST), the Moon will be in the constellation Sagittarius.
👀 🔭 📷 July 14 – Saturn enters retrograde motion.
👀 🔭 📷 July 16 – the Moon (72%) will pass by Neptune (+7.9m) and Saturn (+0.9m). The conjunction will happen around 10:00 a.m. GMT or 5:00 a.m. EST, thus the best time to observe is before dawn on July 16.
👀 🔭 📷 July 17 – Mercury enters retrograde motion.
👀 🔭 📷 July 23 – conjunction of the waning crescent Moon (3%) with Jupiter (-1.9m), which will take place at 3 a.m. GMT (10:00 p.m. EST), so it is better to observe it just before dawn. Both objects will be very low above the horizon.
👀 🔭 📷 July 24 – new moon, the exact time is 7:11 p.m. GMT (2:11 p.m. EST).
👀 🔭 📷 July 28 – conjunction of the Moon (16%) with Mars (1.5 m).
👀 🔭 📷 July 31 – the peak of the broad Southern Delta Aquariids meteor shower, which is active from July 12 to August 23; ZHR = 25, but the radiant will be low above the horizon in the Northern Hemisphere.
A detailed overview of the most interesting events
July 4: the greatest eastern elongation of Mercury
The closest planet to the Sun – which also happens to be the smallest and the fastest in the Solar System – can’t be seen just any day. That’s because it is too close to the Sun for an Earth observer. The best time to observe Mercury is when it appears furthest from the Sun. This configuration is called greatest elongation. The specification “eastern” means that the planet is located to the east of the Sun, so you can see it in the evening, low above the western horizon.
With a magnitude of +0.4m, if Mercury were high in the sky, it would shine almost as brightly as Vega. But in the still light twilight sky, the planet will not look as expressive. The greatest elongation on July 4 is not the best one for observing. Although the angular distance between Mercury and the Sun will be 26° (almost the maximum possible), the planet will be quite low and will go below the horizon about 1 hour and 15 minutes after the Sun. This does not mean that you will have exactly that much time to observe. Practice shows that the optimal time starts when the Sun falls at least 5°-6° below the horizon. At this point (for Kyiv), the planet will be only 4°-3° above the horizon.
July 16: Moon, Saturn, and Neptune in the pre-dawn sky
The visibility of Saturn is slowly improving, and in the middle of summer, it can be seen almost the entire second half of the night. In addition, the planet’s rings are gradually opening up. If you have a telescope, you can see another planet, Neptune, next to the “Lord of the Rings”, which is not visible to the naked eye. Although July 6 is officially considered the day of the conjunction of the giant planets, you will not notice a significant difference in their relative positions. This is because they move very slowly in their orbits.
By the way, the proximity of Saturn and Neptune in the sky means that they are almost in a straight line with the Earth. And on July 16, this “mini-parade” will be joined by a much closer celestial body, the Moon. It will be at its smallest angular distance from the planets at about 10:00 a.m. GMT (5 a.m. EST). Therefore, the optimal time for observations is the pre-dawn hours. Keep in mind that due to the large 72% phase of the Moon, its light will subjectively reduce the brightness of the planets.
July 24: New Moon – time for deep space objects
July is a great month for observing the Milky Way. It contains many nebulae and open clusters. First of all, you can pay attention to the Lagoon Nebula and the Trifid Nebula in the constellation Sagittarius. They are wort your attention – if only because they were among the first objects the new Vera Rubin Observatory pointed its telescope at.
In the small constellation of Scutum (near Aquila), you can find the star clusters M26 and M11, and in Cygnus, the clusters M29 and M39. For astrophotographers, July is the perfect time to visit several nebulae in Cygnus. Among them, the Veil, Crescent Nebula, North America Nebula, and Pelican Nebula are particularly impressive.
If you are just starting to explore the starry sky through a telescope, just point it at the Milky Way and move it slowly – a lot of fun is guaranteed!
July 31: Delta Aquariids meteor shower
From July 12 to August 23, Earth passes through the wide stream of dust particles from the Southern Delta Aquariids. As the particles enter the atmosphere and burn up, they produce the phenomenon known as “shooting stars”. Despite the long history of studying the stream, it is not known for certain where it originates. The most likely hypothesis is that it was formed as a result of the destruction of a large body that broke up into a certain number of comets and meteoroid swarms. It is believed that this is how the complex associated with the comet Machholz (96P/Machholz) appeared. It includes, in particular, comets of the Marsden and Kracht groups, and it is with these groups that the Southern Delta Aquariids are associated.
Technically, the Delta Aquariids can be considered a fairly powerful meteor shower, as the ZHR reaches 25 at its maximum on July 31. However, it should be borne in mind that the radiant (the imaginary point of departure of meteors) remains quite low in our latitudes, which significantly reduces the number of meteors you can see overnight. This year’s Moon phase will be good for observations, however, as it will disappear behind the horizon long before the radiant rises.
The Southern Hemisphere is much more fortunate with this shower, where the radiant rises much higher. While we see about 10 meteors per hour even under perfect skies, the shower will be about twice as abundant for residents of the Southern Hemisphere.
If you still want to try and catch the Southern Delta Aquariids, we recommend choosing a location far away from city lights, and the best time to observe them is approximately between 2:00 a.m and 4:00 a.m (local time). The radiant rises above the horizon at about 22:30 a.m. and culminates at ~3:00 a.m.
