Reprinted for here.
PLANETS AND THE SUMMER MILKY WAY
The interesting thing about sky-watching is the fact that although the seasonal constellations are predictable, what you may see at any designated time is not. Planetary movement and other recurring events take place on different cycles than the background of stars so we can’t always count on seeing the same combination of sights in the sky at the same times. That keeps me in business.
So what we will see in the sky this July is not unusual, but a fortunate arrangement of celestial constituents that will be easy and convenient to view. Four naked-eye planets dot the evening skies this month, with two staging a nice pairing together and beautiful Venus making its reappearance back into the night. Although it might be challenging to spot Venus low in the western sky after sunset during the first half of the month, by the end of the July it will be climbing higher out of the light and easier to spot.
A nice highlight will be the conjunction of Mars and Saturn in the constellation Leo on July 9 and 10. The rust-colored planet and pale yellow Saturn have been slowly creeping closer over the past weeks and will be at their closest on those two dates (although the 10th is technically the closest date, both nights are good for viewing). Included in the lineup is the brightest star in Leo, Regulus, which is on that planet highway called the ecliptic. As a bonus, on July 5 a small crescent Moon joins the group as Mars closes in. That evening going from west to east, you can see the Moon next to the star Regulus, followed by Mars and Saturn. Make sure you start early however, because this gathering will set by 10:00 P.M.
Jupiter is also impressive in the east as the sun sets. The giant planet is at opposition now, meaning that it is on the opposite side of our sky than the sun (think “Sun, Earth, Jupiter” in that order). It appears bigger and brighter in the night sky at this time and is visible in the sky the whole night. Now would be a great time to take out a pair of binoculars and look for the famous features that characterize Jupiter, like the Galilean satellites and the distinct bands of color on the planet. The monster hurricane, the Great Red Spot, is visible with telescopes but not necessarily with average binoculars.
While the planets steal the spotlight this month, don’t forget to pay attention to the summer Milky Way! The hazy band of light extending from north to south is part of the galaxy we reside in and offers many binocular and telescopic sights along the way. The area roughly between Scorpius’ stinger and Sagittarius’ “spout” is particularly wide since that direction is the bulbous center of our galaxy, approximately 26,000 light years away. Rather than individual points of light we see the accumulation of the millions of stars obscured by gas and dust. Right now you can see the Milky Way stretching from the southwest in the direction of the Southern Cross (early in the evening) through the Summer Triangle toward Perseus in the northeast in the early morning hours.
EVENING PROGRAM UPDATE
With so many objects to look for in the skies, it’s difficult to cram everything into one article every month. Consider our planetarium as the next best thing to the real sky, one with a personal “guide” to the stars. An evening program is held on the first Fridays of the month, with sky viewing if the weather is clear. However since it falls on the 4th of July this month, the program has been moved to Friday, July 11. It begins promptly at 8:00 P.M. and reservations are strongly recommended. Call 848-4168.
The Phoenix lander is busily performing its tasks since touchdown on Mars a little over a month ago. What the mission has already done for space exploration was demonstrated by the difficult EDL phase, or Entry, Descent and Landing. Many previous missions were lost in this critical phase, including the predecessor of Phoenix, and since one of the science goals of the mission is to prepare for human exploration, NASA had to prove that landing a craft on Mars has improved dramatically. It appears that goal is well on its way. See http://phoenix.lpl.arizona.edu/ for more information.
The second of two annual opportunities to experience Lahaina Noon comes this month. Between May and July the sun passes directly overhead for areas within the Tropics. During Lahaina Noon objects that are directly perpendicular to the sun, such as flagpoles or fences, have no shadows since the “shadow” would be cast “under” the object. Times vary by location, so check the website for more information: www.bishopmuseum.org/planetarium
Also, aphelion takes place on July 3, the Earth’s farthest point in its orbit around the sun. Coincidentally the Moon is in a new phase at the same time, so the effect of the tides will be enhanced. Higher tides than normal usually occur during this alignment.
Mercury is in the morning sky now, rising around 4:30 A.M. in early July. By the last week it will be too close to the sunrise to spot as it rounds around the backside of the sun to reappear in the evening sky.
For the casual viewer, Venus will be very difficult to spot until mid-month, when it is a little farther from the sun in the western sky at sunset. However the “window” to see it will be short for this month since the planet sets before darkness by 8:00 P.M.
Mars is cruising through Leo, meeting up with Saturn along the way and by the end of the month will pass through the constellation on the way to Virgo. The planet is slowly receding from us in its orbit and dimming as it goes, but is still easily visible to the unaided eyes.
Jupiter reaches opposition on the evening of July 9, rising in the east as the sun sets. If the weather is nice, this is an excellent night to see the four evening planets in the sky. You will need to get somewhere you can see all the way to the western horizon, and starting from that point shortly after sunset (around 7:30 P.M.) look for Venus low in the west, followed by Mars and Saturn close together about halfway up in the western sky and Jupiter rising in the east.
Although Mars and Saturn are set for a rendezvous Saturn’s position changes very little with respect to the starry background. The ringed planet is much farther away than our neighbor Mars, therefore orbiting the sun at a slower rate of speed. Where Mars orbits the sun in almost 687days, Saturn takes 29.5 years!