July starts off as an exciting observing month with the continuation of the Venus/Saturn conjunction from last month. The two planets' closest approach occurred on June 30, but on July 1 the planets are still extremely close together, separated by less than a degree. Venus and Saturn are in the western sky visible as soon as the sun disappears over the horizon. In fact, keen-eyed observers can spot Venus before sunset.
Venus and Saturn will pull apart over the course of the month and head downward. This causes them to appear closer to the horizon at sunset each night. By July 31 they will be over 9 degrees apart.
Venus is the brighter of the two planets. It reaches its brightest for the year midmonth, at magnitude -4.48. Venus has been in the western sky dazzling observers all year. But get your chance to see Venus now, because it will quickly sink below the horizon and disappear near the sun in August.
On July 4, many Americans will be sitting outside at sunset, waiting for the fireworks to begin. Here are some things to look for in the sky while you are waiting for the show to start. First, watch as the sun sets. If it is nice and clear, look to the east. Do you see a darker blue section of sky near the horizon? That is the shadow of Earth cast upon our atmosphere. Now look back to the west. See if you can spot the brilliant Venus before the sun sets. As the sky gets darker, the next object you will see that appears very close to Venus is Saturn, at magnitude 0.44. The brigth star close to Venus after Saturn and a bit farther away will be Regulus, the brightest star in Leo the Lion. The backward question mark shape of Leo's head will be curving around Venus and Saturn. Now look to the south. The brightest "star" in this part of the sky is the planet Jupiter, at magnitude -2.5. If you have a pair of binoculars, aim them at Jupiter. Can you see any moons? If you can only see three, wait an hour and look again. The moon Io should be appearing from behind the limb of Jupiter. Callisto is the moon farthest out. Ganymede is the moon on the southeastern edge of Jupiter (until Io appears, which will be right next to the planet) and Europa is the moon on Jupiter's western side. For another observing target, try catching the Summer Triangle. Don't worry if your fireworks are a couple days before or a couple days after the 4th, because except for the constantly revolving moons of Jupiter, the sky on those nights will appear very similar as the evening of the 4th.
New moon occurs at 8:04 a.m. EDT on July 14. Try heading outside right at sunset on this night and see if you can spy a very young moon before it sets on the heels of the sun. If you don't have success, try again for the sliver of a moon on July 15 in the west northwest. On July 16, the moon makes a gorgeous pairing with Venus, Saturn, and Regulus. All four objects will be within 7.5 degrees of one another. On July 17 the moon will have shifted just off from the planets and star, making a staggered line. The moon next pairs with Jupiter on July 24 and 25, bouncing from its lower right to lower left over the course of these two nights. Full moon is at 8:48 p.m. EDT on July 29.
The Southern Delta Aquarid meteor shower peaks on July 28. But the meteors can be seen over many nights, along with many other minor meteor showers in the summer, making it a great time for campers and others out enjoying the summer sky to catch a shooting star.
For early risers, two planets are hanging out before sunrise. Mars and Mercury are both in the eastern sky. Mars can be found in the constellation Aries and Mercury, which reaches greatest eastern elongation on July 20, rises in Gemini just before the Sun.
