StarWatch: Moravian College Astronomy

StarWatch for the greater Lehigh Valley

MARCH 2015

MARCH STAR MAP | MOON PHASE CALENDAR | STARWATCH INDEX | NIGHT SKY NOTEBOOK

Print Large Sky Charts For 9 p.m. EDT: NORTH | EAST | SOUTH | WEST | ZENITH

Current Solar X-rays:

Current Geomagnetic Field:

967 MARCH 1, 2015: Women Rule the Night: Women lead the pack this week if you’re into making observations guided by the bright moon, Diana, and the Goddess of Love, Venus. Then on March 8, we draw nearer to the Promised Land when our clocks spring ahead one hour on Sunday at 2 a.m. With the longer evening light, Daylight Saving Time is something that I definitely will be cherishing. For this week’s viewing, binoculars will prove handy. They will enhance the pleasure of your observations and are necessary to view at least one distant planet. Start on Sunday with a bright waxing gibbous moon in the southeast at 7 p.m. Approximately one fist held at arm’s length above the moon will allow you to find the two brightest stars of the Gemini Twins, Castor (higher and fainter) and Pollux. To the moon’s left will be Jupiter, which Luna will rendezvous with on Monday. You’ll easily be able to witness the moon orbiting Earth if you go out Tuesday and see how Luna’s position has changed in reference to Jupiter. You will also notice that Luna is now cozying up to the bright star Regulus of Leo the Lion, which will be found to the moon’s left. Wednesday, the moon is located below Regulus. Also on Wednesday, March 4, look low in the West at 7 p.m. to catch brilliant Venus snuggling with Mars (naked eye) and Uranus (binocular). They will fit comfortably within the field of view of average binoculars. Uranus will be that star like object just below Venus. They are extremely tight on Wednesday. By Thursday, Venus and Uranus are separated by over a degree, but Mars included, are still a nice fit in most binoculars. Thursday also finds the full moon, opposite to the sun, rising on the East Coast just after 6 p.m. while the sun sets just minutes before 6 p.m. Set your clocks ahead on Sunday morning, March 8, and you’ll find the sun rising an hour later, but also setting an hour later which will give the illusion that night is now on the run. Spring is just around the corner.

968 MARCH 8, 2015: Dawn Reaches Ceres: Ceres, the bright dwarf planet and first discovered asteroid (1801), is being scrutinized by NASA’s Dawn spacecraft. Launched in 2007, Dawn first orbited the second most massive (third in volume) asteroid Vesta in 2011-12. Then its ion engines drove it onward towards the largest and most massive asteroid Ceres, designated as a dwarf planet by the International Astronomical Union in 2006. Dawn went into orbit around Ceres on March 6. Ceres and Vesta are also considered intact protoplanets, the second last stage in the evolution of the major planets in the solar system. Protoplanets then collided and merged with each other to form the planets that populate our solar system today. Protoplanets between Mars and Jupiter where Vesta and Ceres are found, but not necessarily where they formed, were nudged and pushed by the gravitational forces of massive Jupiter, causing collisions and grinding down their sizes. Vesta and Ceres were lucky in that they suffered numerous smaller hits, but none which were traumatic enough to fracture them into lesser pieces. Basically intact, they represent some of the earliest primordial samples of the solar system. Additionally, both asteroids have major differences in their composition. While Vesta is essentially composed of darker, rockier material, Ceres appears to be more primitive, possessing about a quarter of its mass as mostly water ice. This has led astronomers to hypothesize that Ceres and Vesta formed in two different regions of the solar system and long ago were somehow gravitationally driven into their present-day orbits. Already Dawn has discovered Ceres to be a heavily cratered and gouged world, involved in numerous scrapes and hits with other smaller bodies, similar to Vesta. Unlike Vesta, Ceres also has some vivid bright spots where geysers or cryovolcanic activity, ice eruptions, may be occurring. It’s definitely a new “dawn” for Ceres and icy asteroids in general.

969 MARCH 15, 2015: Santa’s Solar Scoop: This is it! The moment has arrived, and it is what I consider to be the last of the hurdles towards my favorite time of the year—spring and summer. The sun crosses the intersection point of the celestial equator and the vernal equinox, creating the first moment of spring on March 20 at 6:45 p.m. EDT. If you’re not excited about that, I suggest moving to Punta Arenas on the extreme southern Chilean side of Patagonia where you can regale in another six more months of short dreary days and “chilly” weather. Ever since September 22, 2014, the sun has favored the Southern Hemisphere, keeping mid and upper latitudes north of the equator in the cold and dark. Now all that is changing. We’ll have greater light than night until September 23, and if you live at the North Pole, it’s all light and no night. The sun is shining 24/7. I mean, how do you think Santa builds up that big inventory of toys for the Holiday Season? Another caveat of this particular vernal equinox is a total solar eclipse on March 20, visible just a few hours before spring begins over the cold North Atlantic, but also observable from the North Pole. Totality passes two land areas, the steep-sided basaltic Faeroe Islands, a self-governing dependency of Denmark, and Svalbard, an unincorporated area of Norway, “40 times larger than the Faeroe archipelago, a fractured mass of snowy ridges and glacier-filled rifts.” Svalbard is the northernmost place in the world with a permanent population. Its capitol, Longyearbyen, lies at 78 degrees north latitude. Forget about the Caribbean; these are places where real men and women go to see an eclipse and maybe die in the process. But then the moon’s shadow tracks northward to the North Pole where the solar disk is just scratching the southern horizon. Santa and his helpers get to “bathe” in the moon shadow for one minute, 38 seconds. Hopefully, he won’t forget to tweet a picture or two.

970 MARCH 22, 2015: Sky Announces Spring: Spring has arrived, but it is not yet “in the air” because it will take some time before the mid-northern latitudes warm in response to the increasing energy that we are receiving from a sun higher in the sky. On the other hand, the heavens are in full dress rehearsal for the onset of spring. The winter constellations of Orion, Taurus, Canis Major, and Minor are in full retreat and starting to crowd into the southwestern sky. In one month most will be gone. The moon is also growing in brightness in preparation for Easter and starts off on Sunday as a thin waxing crescent about 3-1/2 degrees from brilliant Venus. Try catching the pair about 45 minutes after sundown, around 8 p.m., when they will be about 20 degrees above the western horizon. Because of the steep angle that the moon’s orbit is tilted to the horizon, Luna will actually look like it is grinning at Venus. The smiley moon is also a distinct attribute of spring. By the time it is almost completely dark, around 8:30 p.m., look towards the northeast about halfway up into the sky to view the most famous US star pattern, the Big Dipper. It will be in its early spring location, handle down and cup up. Although in America the Dipper is as famous as any constellation, it was not sanctioned by the International Astronomical Union in 1928 when the sky was divided into 88 areas, and the official patterns recognized. The two top stars of the Dipper, Dubhe (left) and Merak (right) point to the North Star or Polaris which lies about 30 degrees to the left. It appears stationary because the rotating axis of Earth almost points in that direction. If you wait until 10 p.m., the arc of the Big Dipper’s handle will sweep gracefully down and eastward across the sky revealing yet another exceptional spring celebrity, Arcturus, of the constellation of Bootes the Herdsman or the Bear Driver. It is an orangey, evolved giant star, the fourth brightest luminary of the night and a next-door neighbor to our sun at a mere 37 light years in distance. Ad astra!

971 MARCH 29, 2015: Easter Confusion: Sunday, April 5 is Easter. Last year Easter occurred on April 20, and next year Easter is earlier, on March 27. Easter can happen as early as March 22 and as late as April 25. The concept is to keep the season and lunar phase consistent with occurrences at the time of Christ’s resurrection. If Easter is defined as the first Sunday after the first full moon after the vernal (spring) equinox, then there is a 92.2 percent chance that the date will be correct. The rules decreed by the Church were that Easter was to fall on the first Sunday following the Paschal moon (14th day). This moon needed to occur on or after March 21. Day 14 of the lunar month is not necessarily equivalent to the day of the full moon which occurs on average about 14.8 days into the lunar cycle of 29.5 days. Additionally, time zones mandate a less astronomical approach to the moon’s phases since a full moon happens when Luna is exactly opposite to the sun. The full moon is really a moment in time, and it must always occur on two different dates when considered on a worldwide basis. The Paschal or Passover full moon, however, happens on the same date worldwide, and therefore, allows Easter’s date to be globally unified. Although the Paschal full moon must occur on or after March 21, it is derived strictly from a mathematical calculation which can deviate as much as two days from the astronomical time of the full moon. If the date of Easter were not unified in this manner, but based on the real time of the full moon, then Christ’s resurrection would always be in confusion. As an example, if the moon were full at 10 p.m. in California on Saturday March 21, for people on Pacific Daylight Time, Easter would occur on the following day. For the East Coast, three time zones east and three hours later, the moon would be full at 1 a.m. Sunday, March 22. Accordingly, Easter for the East Coast could not occur until the following Sunday, March 29. Oh my “Peeps,” how would the Easter Bunny ever get it right!

[March Star Map]

[March Moon Phase Calendar]