The Fourth of July weekend has a sky full of astronomical sights. If you can see around all the fireworks, you’ll have two of the brightest asteroids near each other, with the Moon near Mars nearby and wonderful Saturn and its rings put on a show it a telescope.
Asteroids 1Ceres and 4Vesta appear to be flying in tandem. (The numbers are the order they were discovered.) They come closest together around the fourth of July. You’ll need a good pair of binoculars or a telescope and a sky chart to tell them from the many other points of light out there. Look a few days before or after the 4th to see how they moved. Despite appearing near each other, Ceres is 46 million miles behind Vesta.
Also, the Moon passes close by Mars on the 5th. Mars is very tiny at 9 arc seconds (Saturn is 18 arc seconds across, and that’s smaller than a large crater looks on our Moon, for comparison.) Sometimes in a larger telescope, you can still see Mars’ color is a mix of gray volcanic rock and salmon-shaded dust.
Mercury is the closest planet to the Sun (always) but did you know it is mostly often the closest planet to the Earth? It holds that title until the 28th when Mars is left as the closest planet to us as Mercury and Venus flee from us to the other side of the Sun in their faster, inner orbits.
In our skies, Mercury shows up in the morning sky, down and to the left of Venus, in the latter 2/3rds of the month. Mercury approaches Venus, getting closest on the 16th, but still doesn’t reach Venus’ height above the horizon.
The Moon joins the scene from the 23rd through the 25th, making a nice photo opportunity. .
Have you seen the live camera views from new cameras installed outside the International Space Station? It’s worth a look to see what you can see from these cameras, although sometimes they are dark when out of range of ground stations or when the ISS is in the Earth’s shadow.
The HD camera is often the most interesting:
and some of the other cameras’ websites show work inside the space station when needed:
Sometimes just before the Sun comes up on the station (every 90 minutes) you can see the brilliant planet Venus as a bright dot rising before the Sun.
Saturn’s rings have a jaunty tilt this year, making it easier to see the space between the rings and the planet. Even the Cassini Division between the A and B rings can be seen at high power. The two main rings are slightly different shades of white. The bright rings make it harder to see some of Saturn’s smaller moons, but Titan is readily visible at magnitude +9. You may see another dot to the west of Saturn; it’s Iapetus, which is brightening up to magnitude +10 by July 3rd, as it turns its brighter face toward us during its 79-day trip around Saturn.
3 Saturn’s and it moons in a telescope’s view. Cartes du Ciel software.
Jupiter is hiding behind the Sun this month. Track it with the SOHO C3 camera http://sohowww.nascom.nasa.gov/data/realtime-images.html from July 14 through August 2.
Even fans of Pluto find it hard to find, even at opposition and at its brightest for the year this month at magnitude +14.1. Pluto is the closest of the Kuiper Belt objects to Earth, unless, as suspected, Triton, in orbit around Neptune, and Phoebe at Saturn may be Kuiper Belt objects that were thrown inward.
ISS sightings are in the morning sky. One of the better overflights (no one will see, since it’s so early!) at 4:37am on July 18th .
The Moon’s monthly closest approach to Earth (perigee) is on the 13th and within 24 hours of the Full Moon. Lining up with the Sun will create larger than normal tides. The Full Moon occurs near the Moon’s perigee for the next three months.
The Sun, on the other hand, is at its furthest from the Earth on July 3rd.