Shropshire Sky At Night – July
With the late summer sunsets we have a longer wait for stargazing darkness.
In fact there are three types of sunsets, or twilight zones, namely, civil, nautical and astronomical. Astronomical twilight occurs when the sun is between 12 degrees and 18 degrees below the horizon.
In the morning, the sky is completely dark before the start of astronomical twilight, and in the evening, the sky becomes completely dark at the end of astronomical twilight. The length of twilight depends on latitude, with the greater the latitude the longer the twilight.
In Shropshire, throughout July, total darkness lasts for about 90 minutes starting about midnight. However this does not preclude the keen stargazer from enjoying the night skies.
Mighty Jupiter, the most observer-friendly planet, is at opposition (directly opposite the sun in the sky) in the middle of the month. Unfortunately it finds itself in the constellation of Sagittarius which is low on the southern horizon. Even so it will provide a spectacular view, far outshining any bright stars on view.
A humble pair of binoculars will easily help you track the four Galilean moons, and a small telescope will reveal a colourful disc together with the major bright zones and dark belts. With the advantage of a six inch telescope, usually a reflector in the cost-conscious amateur circles, one can observe the nightly changes in the cloud tops and of course the Great Red Spot.
A week later the 'must see' object in the Solar System, Saturn, comes to opposition, also in Sagittarius. It will be at its best around 1.30am about 15 degrees above the horizon so planning and an understanding partner is essential.
In addition to the spectacular rings, Saturn has a family of moons, just like Jupiter, the largest being Titan, second largest, after the Jovian Ganymede, in the Solar System. A small telescope can easily show it as a star-type object orbiting its parent planet once every 16 days or so.
For the early risers Venus can be spotted close to Aldebaran, the eye of Taurus the Bull, at the beginning of civil twilight (around 4am). As the month progresses Venus steadily climbs higher into the sky, with the 17th providing an excellent photo opportunity as she passes close to a crescent moon.
Finally the elusive Mercury offers a challenge to those with a good morning horizon. However, do not search for the planet with any instrument after the sun starts to rise.
The International Space Station makes a return to Shropshire eyes throughout the month, but unless you are a night owl you will have to wait until later in the month for evening viewing.
An easily missed 38 minute penumbral lunar eclipse will next take place on July 5, between 04.07 and 04.45, when the Moon travels only through the outer, fainter part of the Earth's shadow, or 'penumbra'. The penumbra causes only a slight darkening of the Moon's surface, with the Moon still exposed to some direct sunlight.
Some spectacular sights and images can be captured depending very much on the contents of the atmosphere at the time, so get your cameras out and start clicking.
Shropshire Astronomical Society always welcomes experienced or novice stargazers, but has suspended all meetings and public events for the foreseeable future. For further information visit www.shrophire-astro.uk
Steve Szwajkun is a member of Shropshire Astronomical Society
