This will be an every-two-months guide to what you can see in the night sky, geared to mid-latitude northern hemisphere observers. The original post with more detailed guidance can be found here. What can you expect to see in May and June 2014?
Moon Phases: Full on May 14th; new on May 28th. Ancient people, who observed the sky much more closely than most modern humans, knew that Moon appeared larger at some times than others. We know now that this is because its path around the Earth is not a perfect circle, but an ellipse that brings it sometimes closer and takes it sometimes farther away. The difference really is noticeable, as you can see from these comparison images. Perigee is the point of closest approach to Earth; apogee is the point of greatest distance.
This is most apparent when a full moon occurs near perigee, since the Moon’s nearness makes it much brighter. The much-hyped “super moons”—more a media-invented term than anything astronomers actually say—take place at these times.
May’s full moon on the 14th is not a super moon, but it does occur near perigee on the 18th. Barring clouds, it should be nice and bright. That will be a good time to go outside and read a large-print astronomy book!
Planets: Mercury is the most difficult of the eight classical planets to spot because of its proximity to the Sun, both from our viewpoint and in actuality.
Mercury never gets farther away than 28 degrees from the Sun, about three times the width of your fist held at arm’s length. On the evening of May 25th, it will be 23 degrees away from the Sun in the western sky. Wait until the Sun sets to be safe, then use binoculars to spot the innermost planet about halfway between the Sun and the bright, hard-to-miss Jupiter. You can try for a few nights before or after this optimum date, but don’t wait too long. Mercury moves fast—it is, after all, named for the fleet-footed messenger of the gods.
Jupiter follows Mercury behind the setting Sun, getting lower in the western sky as the month progresses.
Mars is nicely positioned for viewing in the early evening and does not set until well after midnight. In mid-May, look for an orange-reddish “star” almost due south. Don’t be confused by the bright (real) star Arcturus! It is higher in the south and a little east (to the left) of Mars.
Saturn, the universal favorite planet to see through a telescope, lies farther to the east. It reaches opposition on May 10th.
A superior planet is simply one that orbits farther from the Sun than does the Earth; opposition just means opposite the Sun in the sky. In practical terms, a planet at opposition is due south at midnight.
Saturn is moving farther from the Sun in its own elliptical 30-year orbit, but it has been getting brighter with each succeeding opposition. The key to this apparent paradox is that the angle of tilt of Saturn’s rings has been increasing as we view them. Edge-on in 2009, the northern surface is now tilted toward us by 22 degrees. The rings are very reflective, since they are composed of mostly water ice.
Meteor Showers: There are a couple of nice showers this month. On the night of May 6th, the Eta Aquarid meteor shower provides a nicer show for our southern hemisphere neighbors than for those of us who live north of the equator. The dust particles responsible for it come from the most famous comet of all, Comet Halley. Meteor showers occur when Earth crosses the path of comet, which strews dust all along its path.
For northerners, the radiant (see this original post for an explanation) is highest in our sky after the sun has already risen; our best viewing hours are just before dawn. For folks in southern latitudes, this is one of the best showers of the year. It was unusually strong in 2013 and that may repeat this year.
An unnamed shower from a comet discovered in 2004 (Comet 209P LINEAR) MAY (and I emphasize may) produce a spectacular shower on May 24th. Some predictions are for a full-fledged meteor storm, with up to 400 meteors an hour, one every ten seconds or so. This one is better positioned for us in the north, as the radiant is well to the north.
Deep Sky: A view to the south this month is dominated not only by Jupiter and Mars, but by three bright stars as well. The red giant Arcturus is the brightest of these, and is the fourth brightest star in the sky, not including the Sun. Moving from east to west (left to right) we see Spica and Regulus, respectively the 15th and 21st brightest stars.
Even though the celestial sphere looks like a dome, with stars of different brightness all the same distance away on a curved surface, it does in fact have a third dimension. A star’s brightness depends not only on its luminosity (its inherent brightness), but also on its distance. Not surprisingly, Arcturus is the closest of this triplet at 37 light years, and Regulus is 79 light years away. That leaves Spica at a distance of 260 light years. The easy conclusion is that Spica is the most luminous of these three.
To the north are two other bright stars. Capella lies low in the northwest early in the evening on its way to slipping below the horizon. Vega lies low in the northeast, and is rising higher in the sky as the night progresses. Almost directly above the north star is the upside-down Big Dipper asterism.
A deep sky object that requires a telescope but is well worth the effort to get yourself to one (here is information about Lynchburg College’s May observatory open house) is M51, the Whirlpool Galaxy. Many are familiar with the spectacular Hubble Telescope image:
But no one actually sees anything like this looking through a telescope; such images are the result of long exposures on a digital camera. Viewing time on a world-class telescope is too valuable to assign to a feeble instrument like the human eye! This is more like what you would see with the Gilbert 20-inch telescope at the Lynchburg College Belk Observatory:
The Wikipedia article on M 51 is a great source for more information.
Looking south, 10 pm, May 15th.
Looking north, 10 pm, May 15th.
Southern-facing view in chart form.
Northern-facing view in chart form.
Moon Phases: Full on June 13th; new on June 27th. In the summer, full moons are lower in the sky (more southerly) and the Sun is higher (more northerly). In the winter this is reversed: full moons are high on winter nights and the Sun is low during a winter day. All of this is from a northern hemisphere perspective.
Planets: A testament to just how fast Mercury moves is this: it was at its greatest distance from the Sun from our Earthly perspective on May 25th. Less than a month later, on June 19th, it passes on our side of the Sun, 4 degrees south of it.
Jupiter is moving ever closer to the setting sun, only one hour behind it at the end of June.
Mars and Saturn are the two brightest planets in the southern sky, and they move closer to each other throughout the month. They will pass each other in August. Saturn, the more westerly of the two, sets at 3:30 am on the first of the month and 1:30 am at the end. On the night of June 10th, Saturn and the nearly full moon will pass very close to each other.
Venus is the bright “morning star”, rising two hours before the Sun in the east.
Meteor Showers: The June Boötids are a notoriously variable meteor shower that may (or may not) peak on June 27th. The radiant is overhead at 9 pm and visible all night long.
Deep Sky: Another of those get-to-a-telescope-if-you-can objects is M 101, the Pinwheel Galaxy. A telescope of 16-inch or greater aperture will reveal structure in the spiral arms, provided you are under a dark sky, preferably with no moon.
Seeing structure in a dim object requires patience, and reveals as well as anything the difference between just looking (giving it five seconds and not seeing anything) and seeing (taking the time needed). Your eyes should be dark adapted, and you should use averted vision, not looking directly at the object. This lets you see more detail. It works because the central region of the eye has only cones, cells which detect bright light and color and are not particularly useful at night. Just a little off to the side, the concentration of rod cells is much higher, and rods detect dim light in black and white.
Here is more about the Pinwheel Galaxy.
Summer Solstice: Occurs at 6:51 am EDT on June 21st. This marks the farthest north that the Sun travels in our sky, the official beginning of summer in the northern hemisphere and winter in the southern hemisphere, and the longest day of the year for the north. The latest sunset, however, occurs on June 27th, so it seems like the longest day. If you want to celebrate the solstice in a truly old school way, this is how to do it.
Looking south, 10 pm, June 15th.
Looking north, 10 pm, June 15th.
Southern-facing view in chart form.
Northern-facing view in chart form.