StarWatch: Moravian University Astronomy

MARCH 2025

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

Current Solar X-rays:

Current Geomagnetic Field:

lunar phases

1489 MARCH 2, 2025: Moon Dances with the Planets: This StarWatch is being sent early. Several weeks ago, the moon played among all the planets in the evening sky, except Mercury which rose before sunrise. Now Mercury has scurried to the eastern side of the sun and is visible low in the west 30 minutes after sundown. Technically, all of the seven planets are in the evening sky right after sunset. Still, unless you possess some alien technology that can shroud the sun and create near-perfect dark sky conditions, you will be unable to see them all. On Saturday, March 1, immediately after sunset, the planetary lineup will be as follows: Saturn, Mercury, Neptune, (crescent moon), Venus, Uranus, Jupiter, and Mars. Don't forget to look down at Earth to make it an even eight. * The media has been billing this lineup for weeks, misleading the public into believing that all the planets will appear like a string of pearls garnishing the twilight sky. The easily seen planets will undoubtedly be pretty, with Mercury, the moon, brilliant Venus, Jupiter, and Mars, like gems curving across the early evening sky. Saturn will be just nine degrees from the sun and seven degrees above the horizon at sunset on March 1. * By 6:15 p.m., the ringed world will be only three degrees above the horizon, while Sol will be only five degrees below the horizon during civil twilight. Simply put, there will be enough light in the sky for all to see what they are doing. Venus should be easy with the unaided eye, but initially, observers will require binoculars for Mercury. Nautical twilight follows civil twilight when shipboard navigation becomes possible using the 57 Select Stars cataloged in the Nautical Almanac. Finally, astronomical twilight occurs when the fainter stars begin to peak through the darkening heavens, ending when the sun is 18 degrees below the horizon. By 6:45 p.m., as nautical twilight deepens, Mercury should become visible to the unaided eye about five degrees above a nearly flawless western horizon. Neptune will be only two degrees, four moon diameters to the left of Mercury; however, Neptune will be 4000 times fainter. Unless you are Superman supported by alien technology and can fly off into space, your chances of viewing Neptune are essentially zero. So Saturn and Neptune will be no-shows because of their proximity to the sun. * The upside will be the trifecta of solar system objects visible on March 1. They will include the goddess of beauty, Venus, the 5.5 percent razor-thin waxing crescent moon with plenty of earthshine, and most likely the messenger god, Mercury. Observe during nautical twilight, 7:15 p.m. Go here to view the full planetary parade on Saturday, March 1. * On Tuesday March 4, the 31 percent crescent moon is five degrees to the right of Uranus, high in the west by 6:45 p.m. Binoculars should quickly pick up the second last planet as a faint star-like object nearly one binocular field left of Luna, particularly if you wait another 30 minutes until conditions are well into astronomical twilight. The picture below represents a locator map for finding Uranus on March 4. The more positive the number associated with the star, the fainter it is, but all should be easily visible through binoculars. Face east and place the moon on the right side of your field of view. Uranus will be the faintest object in the configuration seen below. As the week continues, the moon glides higher into the sky, missing Jupiter by nearly eight degrees on Wednesday, March 5. By Saturday, March 8, Luna, now a much brighter waxing gibbous moon, more than half lit, snuggles up to ruddy Mars with less than 1.5 degrees of separation, a nice view through binoculars. By Thursday, March 13, at 7 p.m., Mercury and Venus are positioned 5.5 degrees apart and five degrees above the western horizon at 7 p.m. Have fun watching the sky this week and next week. There will be some beautiful sights and more to come. Ad Astra!

1490

MARCH 9, 2025: Total Lunar Eclipse This Friday

The moon hides in Earth's shadow on the morning of March 14 to produce what should be a very colorful total lunar eclipse across the Americas. The drawing below comprises authentic images taken by the author on the bone-chilling morning of December 21, 2010, and then added to a computerized mockup of the eclipse using Software Bisque's The Sky. The umbra (main shadow) and penumbra (secondary shadow) of Earth are represented by different shades of grey. While the moon is within the penumbra, decreasing light from the Earth, blocking more and more of the sun's light, causes the moon to have a dusky appearance, especially as Luna gets closer to the penumbra-umbra boundary. The diminution of light is represented in the photos but not in the drawing. Any location on Luna in the umbra sees Earth completely covering the sun. Lunar totality happens when the moon is entirely immersed in Earth's umbra. The stages of the eclipse are given in military time, a 24-hour system with hour: minute: second calculated by NASA when the event occurs. Also note that the umbra and penumbra are invisible against the black sky and, if precisely represented in the drawing, would become darker towards the umbra's center. Enjoy the beauty of a total lunar eclipse. Ad Astra!

A Circle of Total Lunar Eclipses: Top left moving clockwise, May 16, 2022, Nov. 19, 2021 (very deep partial), Dec. 21, 2010, Nov. 8, 2022. Timings of the March 14, 2025 total lunar eclipse provided by NASA. Diagram photos, Dec. 21, 2010, as well as all other images, Gary A. Becker, except where noted.

1491 MARCH 16, 2025: The Profile of Spring: A better word could not be chosen—Spring! For the next six months, the Northern Hemisphere will be basking in the bright light of a sun that will be shining north of the equator and warming us because of its more directly focused energy. The sun crosses zero latitude, the equator, on Thursday, March 20 at 4:59 a.m., EDT, balancing the light of day with the darkness of night, the time of the vernal equinox (equal nights, equal days) for virtually the entire planet. Then Sol will continue its rapid ascent northward favoring the Northern Hemisphere, while its influence wanes south of the equator. As I write this blog, one of my friends and former students, Adam Jones, is waiting for a flight back to Sydney, Australia. Adam spent three months as Chief Meteorologist at the South Pole. At the well bottom of the Earth, Adam celebrated the summer solstice on December 21 and New Year's Day a week later with the sun circling the pole's frozen landscape similar to the twirling view seen on a spinning merry-go-round. Sol was at its greatest altitude on December 21, 23.5 degrees above the snow-crusted polar horizon. The start of the New Year was marked in celebration against a crystal blue sky. Some participants wore shorts, although there were not many of them in the video Adam sent to me. The warmest day that I saw on Adam's forecast reports scratched zero Fahrenheit. However over the intervening months as the sun has lowered, so have the temperatures; -20, -30, -40 and as I "pen" these words a brisk -67 degrees Fahrenheit. * At Russia's Vostok Station nearly 800 miles distant, but at 11,444 feet in elevation (The South Pole is at 9,301 feet above sea level), the temperature was even colder, -76 degrees F. Vostok holds the record for the world's coldest temperature, recorded on July 21, 1983, a bone-numbing -128.6 degrees F. At the South Pole, the sun will set on March 20, among the fanfare of a few stalwart staff members who will winter over there, along with enough supplies and alcohol to get them through the dark days of the six months that lie into the future. Because of atmospheric refraction, sundown is not always sundown. Sol can unexpectedly pop above the horizon at times for several weeks after it has officially set. * However, in the Lehigh Valley, winter is definitely on the wane. These seasonal changes are a result of the tilt of the Earth's axis, the imaginary line about which our planet rotates (spins). The angle of inclination is measured with respect to the perpendicular of Earth's orbital path around the sun called the ecliptic. In the Lehigh Valley, Sol will be gaining altitude rapidly changing the browns that we have become so used to viewing into the verdant greens of spring. The deviation of the sun from the equator, north and south, is the same amount that our axis is tilted. * Sol will continue to move northward until it has reached 23.5 degrees above the equator, a position called the Tropic of Cancer, its northern limit. That happens on Friday, June 20 at 10:42 p.m., EDT. Locally, we will be flooded with nearly 15 hours of sunlight, while for residents living just north of Fairbanks, Alaska on the Arctic Circle, 23.5 degrees south of the North Pole, the sun will not set at all. At the top of the world, just like at the South Pole, at the opposite time of the year, Sol will remain visible for a period of six months. * Watch the sun's noontime altitude climb during the next three months and note how shadows will be shortening. Watch the sun's rising locations shift more and more to the north of east as the sun moves northward towards the Tropic of Cancer and the summer solstice. Sol's setting positions will also gradually move to the north of west. The vernal equinox is indeed the start of the astronomical season of light. Happy springtime to all who favor the sun. Ad Astra!

1492 MARCH 23, 2025: Peeking Around the Moon: Several years ago, I remember having a rough night's sleep. When counting asteroids and taking melatonin did not work, my wife asked why I was so restless. I said, "Lunar librations… I'm trying to visualize them in my mind." Her response was, "Why are you just picturing them? Place an order at the State Store." "Not libations," I responded, "librations, the wobbling effect that the moon goes through as it orbits the Earth." "Can't help you there," she replied, promptly falling back to sleep. * There are three of them, two in longitude (east-west) and one in latitude (north-south). Over a 30-year period, they allow astronomers to view 59 percent of the lunar surface, not just the standard 50 percent that most individuals believe can be observe. The never-before-seen far side of the moon was first imaged by the former Soviet Union's Luna 3 in 1959. * The moon keeps its same face pointing towards Earth, a synchronous dance that allows Luna to complete one rotation (spin) in exactly the same interval of time that it needs to complete one revolution (orbit) around the Earth. If the moon did not rotate, we would have been able to map its entire surface from Earth. While the moon's rotation takes place at a uniform (angular) rate, it is also revolving around the Earth in an elliptical (oval-shaped) orbit, moving towards and away from our planet, constantly changing the gravitational attraction between these two bodies. * At perigee, the moon's closest location to Earth where the mutual attraction for Earth and moon is strongest, Luna is orbiting at its greatest velocity. The moon's angular change due to rotation lags behind the more rapid angular change due to its orbital motion, and we get to peek around the moon's eastern limb (side). When the moon reaches apogee, its greatest distance from Earth, we see it face on again with no libration in longitude. Here, the moon is moving at its slowest orbital pace but continues to rotate at a constant angular rate. Rotation outpaces Luna's orbital motion. We now peek around the moon's western limb. * Another smaller diurnal (daily) libration in longitude is at its maximum when the moon rises and sets. When Luna rises, our terrestrial position is "higher" than the moon's location, and we get a little peek over the eastern limb, similar to being on the summit of a high mountain and being able to gaze over a greater distance to the horizon. Likewise, we have a view a little beyond its western limb when the moon sets. Those are the two geometrical librations in longitude, but there is also a libration in latitude. * The moon's axis is tilted about 1.5 degrees to the perpendicular of its orbital plane, but the plane of the moon's orbit is also tilted by about 5.2 degrees to the plane of Earth's orbit (the ecliptic), causing the moon to have a total tilt of about 6.7 degrees in latitude. Again, think of being on a mountain. When the moon is located below the ecliptic, we have a view beyond the lunar North Pole, but when the moon is above the ecliptic, we now get a peek past the lunar South Pole. * Keep in mind that while these librations are occurring, the moon is moving closer and farther from the Earth as well as above and below the ecliptic plane, which is tilted to the celestial equator. It’s a roller coaster ride that can be observed by clicking on this link that will lead you to an amazing year of librations compiled by NASA's Lunar Reconnaissance Orbiter during 2019. I have also enclosed two slides modified from a Launch Pad Astronomy video that helps to explain the major lunar librations more visually. Having been able to envision these three librations in my mind and write descriptively about them, I feel the need to celebrate, taking my wife's advice with a libation. Ad Astra!

1493 MARCH 30, 2025: