What’s Up This Week – June 20 – June 26, 2005

View of Mars. Image credit: NASA/JPL. Click to enlarge.
Monday, June 20 – Have you checked out Mars lately? Today Mars crosses the celestial equator positioning it higher amoungst the constellations. Since we are focusing on planetary motions this week, see in your mind’s eye that we are on a type of racetrack. Since Earth is closer to the Sun than Mars, we move around that inside track much quicker, and right now we are coming up behind Mars at a speed of 23,500 mph, which means Mars getting bigger and brighter every day – and will be spectacular by October. Now rather “football” shaped, be sure to look in a telescope to see if you can catch a glimpse of the polar caps. Be sure to check next week when the crescent Moon and Mars make a pleasing conjunction in the morning sky!

Tonight on the lunar surface, use binoculars to spot the dark oval of Grimaldi just south of central on the terminator. If you chose to scope, look for the great form of Pythagorus to the north and its sharp central peak.

Although the peak time for the June Ophiuchids happened in the early morning hours, you still might catch some of the stream tonight. Its radiant is near Sagittarius and the fall rate varies from 8 to 20, with possibility of many more.

Tuesday, June 21 – Today the Sun achieves its highest point for the year at midday for the northern hemisphere. Known as the Summer Solstice the exact moment occurs at 06:46 UT, and also marks the Winter Solstice for our friends in the Southern Hemisphere.

For most observers, the Moon will appear to be full, but will not actually reach that point until 04:14 UT tomorrow morning. Just take some time to watch it rise! Known as the Rose Moon, Strawberry Moon and Honey Moon, if atmospheric conditions are right, you might see an orangish tint to its form, but the real fun is “moon illusion”! Everyone knows the Moon looks larger on the horizon, but did you know this is a psychological phenomena and not a physical one? Prove it to yourself by looking at the rising Moon upright… It looks larger, doesn’t it? Now stand on your head, or find a way comfortable to view it upside down… Now how big is it?

Wednesday, June 22 – Today celebrates the founding of the Royal Greenwich Observatory in 1675. That’s 330 years of astronomy! Also on this date in history, in 1978 James Christy of the US Naval Observatory in Flagstaff, AZ discovered Pluto’s satellite Charon.

Tonight let’s race ahead of the rising Moon and capture comet 9/P Tempel 1. (Remember there are very accurate night-by-night locator charts on Heavens Above.) If you can find Jupiter, then you’re definitely in the neighborhood to locate this comet. Just to Jupiter’s east is Omicron Virginis. Consider this to be “one step”. Now take two more “steps” east and you are in the general vicinity. While the comet is still rather faint for smaller instruments, magnitude 10 should still be within the reach of most backyard scopes.

Thursday, June 23 – The time has come at last! In case the weather should turn cloudy, be sure to go out tonight and enjoy the western horizon just after sunset. The grouping of Venus, Saturn, and Mercury low in the west-northwest should not to be missed. Venus, by far the brightest of the three, sits central. Mercury will appear just slightly more than one degree to Venus’ lower right and Saturn about two and half degrees to Venus’ upper left. Timing is critical, so start your observations about 30 to 45 minutes after sunset.

Once you’ve viewed the planets, let’s set a telescope toward 6 Comae, just east of Denebola. Less than a degree (50′) to its southeast, you will find the spectacular M99. Discovered by Mechain in 1781 and then confirmed by Messier, this magnitude 10.5 spiral beauty has wonderful structure and a highly apparent arm to smaller scopes on the west side. Return to 6 Comae and travel a half degree to the west and you will find M98. Again discovered by Mechain in 1781, this nearly edge-on spiral has a bright nucleus and is very extended for the larger scope.

Friday, June 24 – On this day in 1881, Sir William Huggins makes the first photographic spectrum of a comet (1881 III) and discovers the cyanogen (CN) emission at violet wavelengths. This discovery caused near mass hysteria some 29 years later when Earth passed through the tail of Halley’s Comet.

Our trio of planets, Saturn, Venus and Mercury have now come together within two and a half degrees of each other, making the area small enough to fit easily within most all binocular’s field of view. The orbital motions of Venus and Mercury are carrying them past Saturn, so watch as the “Ring King” drops away over the next few days. Please take the time to look at the extraordinary display of planetary motion!

Since Huggins viewed a comet 124 years ago on this night, why don’t we? The “Magnificent Machholz” is still around and sailing through Canes Venetici. Locate bright Cor Caroli and head south about two degrees to identify star 14. You will find C/2004 Q2 just about a degree to its southeast.

Saturday, June 25 – The planetary show just keeps getting better as our trio reaches its tightest configuration after sunset tonight. Saturn, Venus and Mercury are now within a degree and half of each other, and easily covered by your thumb held at arm’s length. Their relative positions planets are changing rapidly, with Saturn dropping to the lower left of Venus and Mercury to the lower right. This will be an awesome photographic opportunity and I wish all of you success and clear skies!

Sunday, June 26 – Today is the birthday of none other than Charles Messier, the famed French comet hunter. Born in 1730, Messier is best known for cataloging the 100 or so bright nebulae and star clusters the we now refer to as the Messier objects. The catalog was to keep both Messier and others from confusing these stationary objects with possible new comets. In 1949, asteroid Icarus was discovered on a 48-inch Schmidt plate made nine months after the telescope went into operation, and just prior to the beginning of the multi-year National Geographic – Palomar Sky Survey. The asteroid was found to have a highly eccentric orbit and a perihelion distance of just 17 million miles, closer to the Sun than Mercury, giving it its unusual name. It was just four million miles from Earth at the time of discovery, and variations in its orbital parameters have been used to determine Mercury’s mass and test Einstein’s theory of general relativity.

And what of Mercury? Tonight both Mercury and Venus have moved above Saturn by about a degree and a half, almost doubling that separation. Get out your scopes, because Venus and Mercury now are only 0.2 degrees apart. But wait… The show gets even better tomorrow night! Be sure to look for next week’s “What’s Up”!

For now, the Moon rises later and later each night allowing us more opportunity to study the deep sky! May all your journeys be at Light Speed… ~Tammy Plotner