By Roger Linnett
This month serves up a sweet little visual treat for our enjoyment; 4 of the 5 planets visible with the naked-eye will all rise together in the eastern pre-dawn sky.
Plus we’re going to encounter a meteor shower, those fiery, cosmic sprinkles, which peaks the first week of the month, and for the metaphorical cherry on top – a crescent new Moon joins in the planetary “flash mob” at the beginning, and again at the end, of the month.
Mercury, Venus, Mars and Jupiter will all be within a few degrees of each other from our line of sight on Earth; their most compact grouping coming on the mornings of May 11and 12.
You will need to have a clear view of the eastern horizon, or be able to get high enough to see over the neighbor’s rooftops. Of course, the darker the location, the better: try to avoid having street lights, etc., along your line of sight as they inhibit your eyes adjusting to the night sky.
Mercury will definitely be visible with binoculars, and possibly to the unaided eye, all month. It’s very low in the sky, below Venus, “the Morning Star,” the brightest object in the early morning sky. Mercury shines only one-fourth as bright as Venus.
Mars will be the hardest of the group to see. It begins the month hidden in the Sun’s glare, and may be too low in the sky to see without binoculars until mid-May.
Jupiter is also very low at the beginning of the month, but rises quickly, and on the mornings of May 11and 12 is a mere half of a degree (the apparent diameter of the Moon) above Venus, and a little dimmer.
If you follow the quartet from night to night, notice the way Mercury moves relative to Venus. At the beginning of the month it sits just below Venus. It moves a little to the right each night until the 11th, and thereafter moves back to the left, catching Venus on the 19th, and then leaving her behind in their age-old promenade around the Sun. This apparent back and forth motion is an optical illusion similar to passing a car on the freeway. The car appears to us to be moving backwards, but we know it’s not.
Mars is positioned below and left of Venus and Mercury. Its pinkish cast, enhanced by our atmosphere, makes it easy to differentiate from nearby celebrities.
After their brush with Jupiter, Venus and Mercury close in on Mars as it rises out of the morning twilight. It moves steadily higher with each passing night.
Jupiter moves noticeably from night to night, again due to an optical illusion caused by the relative motion of the planets in their orbits.
After it passes Venus on the 11th, Jupiter continues to move up and away as Venus and Mercury pursue Mars, coming closest on the 23rd.
As the month ends, Mercury and Venus sink down into the Sun’s glare, as they pass behind it, while Mars and Jupiter climb higher each night, rising earlier each month, and will be visible at night for the rest of the year.
The Eta Aquarid meteor shower, which peaks this year on the morning of May 6, is the first of two showers that occur each year as a result of the Earth passing through the trail of dust left by Halley’s Comet; the second being the Orionids, which we will encounter during the second half of October. You should be able to see 12 to 15 or more an hour during the peak, but some meteors will continue to arrive for a few weeks thereafter.
These meteors are, in fact, just grains of sand and dust blown off the comet as it plows through the so-called “solar wind,” which continuously streams from the Sun.
Their bright trails are the result of hitting our atmosphere at an amazing 30 miles per second — over 100,000 miles per hour!
The meteors appear to originate in the constellation Aquarius, near the seventh brightest star, designated Eta, hence their name, which rises about 3am at this time of year, a couple of hours before morning twilight.
Looking to the east, locate the Square of Pegasus; the four bright stars form a large diamond. Aquarius is the area of sky to the right. The meteors’ trails will point back toward that spot, but can appear from just about anywhere above and to the sides of that general direction.
Bundle up good and warm, take a thermos of something hot, clean your binox lenses, break out a lawn chair or chaise, kick back and enjoy the show. These planets don’t get together for family pictures very often, so take advantage of this rare opportunity.