StarWatch: Moravian University Astronomy

FEBRUARY 2023

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

Current Solar X-rays:

Current Geomagnetic Field:

lunar phases

1381 FEBRUARY 5, 2023: Green Comet, Eagles' Fan?: Is green comet, C/2022 E3 (ZTF), an Eagles' fan? It most certainly should be, but its greenness has only been discernable in guided digital exposures of this interloper into the inner solar system. The comet has brightened significantly since I first observed it on the morning of January 16 just before moonrise. It certainly was not spectacular from a suburban locale, but it was visible. My rule of thumb is that if I find something faint, then I have to go back and find it several more times to verify its authenticity. I did that four times, as my eyes became better adapted to my suburban backyard conditions. * C/2022 E3 (ZTF) was closest to the sun on January 12 and closest to the Earth on February 1, but that does not mean that the comet will immediately fade. I viewed it for the second and third times on January 28 and the 29th, both around 2 a.m. Its location on the 28th was close to the two end stars of the Little Dipper's bowl and several degrees farther away the following night. On both mornings with 10x50 binoculars, C/2022 E3 (ZTF) was easy to spot. I independently estimated its magnitude at +5.5 by defocusing the 5th and 4th magnitude stars of the two other luminaries that create the bowl of Little Dipper (Ursa Minor), and then refocusing on the comet. My brightness estimate was consistent with other observers' assessments. The coma diameter was about 15 minutes of arc, about half the angular width of the moon. * The latest evaluations of the comet by observers on February 4 showed that it was about as bright as my late January estimates, after brightening to magnitude +4.4 on February 2, then fading. The most recent estimates are about 11 times the brightness intensity of its predicted illumination. This could make it a near naked eye object from very rural locations except for the waxing gibbous moon illuminating the sky and drowning out its diffuse light. * The moon is full on February 5. After that date Luna rises much later each evening allowing the comet to be seen with binoculars in a moonless sky right after darkness. A map has been published here created by Guy Ottewell, author of the yearly Astronomical Calendar which is an excellent resource for sky watching enthusiasts. * On February 5 the moon is full which means that it will rise and set opposite to what the sun is doing, with Luna being visible all night long. On the 6th moonrise happens at 6:19 p.m., too early to catch the comet in a completely dark sky, but still worth giving it a try because it will be so close to the star Capella, the 6th brightest luminary of the nighttime sky. Refer to the map link above. On February 7 moonrise happens at 7:20 p.m. and all systems will be "a go," to view C/2022 E3 (ZTF) in a completely dark sky. View after 7:00 p.m. and before moonrise 20 minutes later. It will still be near Capella, but now below and slightly to the right of this bright star. * No one knows exactly what to expect with regards to its brightness, but as David Levy, an avid observer and discoverer of many comets once said, "Comets are like cats; they have tails and do precisely as they want." Let's hope that not only the Eagles will fly to victory, but that C/2022 E3 (ZTF) will give us an out-of-this-world performance too. Ad Astra!

1382

FEBRUARY 12, 2023: Amorous Heavens: Not So Fast!

Forget the flowers, the expensive chocolates, the overpriced romantic candlelight dinner and just step outside because love is literally in the air. Look to the west around 6:15 p.m., and wrap your arms around your significant other. There you will notice two brilliant star-like objects shining with a steady light. That is a sure indicator that you are viewing planets and not distant luminaries. Planets don't twinkle as much as the stars because they are not point sources, but actually tiny disks too small for the average human eye to distinguish, and therefore, less affected by Earth's turbulent atmosphere which causes the stars to twinkle or scintillate. * Jupiter will be higher above the horizon and the fainter of the pair, but positioned close enough to Venus, the Goddess of Love, to be easily seen in the same skyscape. Bring the champagne and make a toast to this beauty of the heavens which may be Valentine's Day on the cheap, but indeed, the sky will produce a memorable moment that will make this Holiday of Love special. I don't even have to go outside because my front door opens up to this magnificent view, but my wife is not falling for just the simple champagne toast. A sumptuous seafood dinner will follow sometime within the following week because I have to teach on the evening of the 14th. Maybe we'll treat ourselves to Mickey D's for lunch. * What you will be witnessing is the onset of a spectacular performance by Venus that will keep her in the limelight for the next five months, climbing higher into the nighttime sky and stretching farther and farther away from the sun until the fourth day of June, when Venus will be at its greatest eastern elongation, its greatest angular distance to the east of the sun (45.4 degrees), so high above the western horizon that she will not set until just 15 minutes before midnight. That is extraordinary for this latitude. * After June 4 Venus will begin to move back towards the sun, disappearing from view sometime in late July to pass between the Earth and Sol on August 13, a moment known as an inferior conjunction. * However, as attractive as Venus appears to be in the evening or morning sky, her beauty is only skin deep. Beneath the luster is a planet that would cook, poison, crush, suffocate, and dissolve any astronaut lover that attempted a landing without being properly safeguarded by an enormous amount of special protection. * Venus' atmosphere is 95 percent carbon dioxide with cloud layers of concentrated sulfuric acid and even some hydrofluoric acid to boot. Eventually, a descending spacecraft would break free of the acid drizzle only to feel the temperatures increase upon landing to nearly 900 degrees Fahrenheit. There would be no relief at the poles or on the nighttime hemisphere of the planet. It's the same temperature everywhere. The force of the atmosphere pushing down upon a voyager would top off at 93 times the Earth's pressure (14.70 pounds/square inch) or just over 1350 pounds per square inch on Venus, enough downward push to cause some volcanic mountains to flatten into pancake-like structures. * I'm sorry to report that despite her outward beauty Venus is "the black widow" of the solar system. Flowers, champagne, chocolates, and dinner might just be in order after all. Happy Valentine's Day to everyone and give Venus a hardy salute as you and your Special Someone make your way to your favorite restaurant. Ad Astra!

Venus and Jupiter on Valentine's Day, February 14, 2023. The sky is all about love. Image produced by Stellarium...

1383 FEBRUARY 19, 2023: Follow the Moon to First Quarter: This was not a good week for green. The Eagles lost to the Chiefs, and green comet C/2022 E3 (ZTF) has steadily faded from a somewhat respectable binocular brightness in late January to become much fainter at the present time. * However, there is another very familiar object that will be gaining prominence during the next two weeks before it fades again in its monthly cycle, and that is the moon. Right now (Sunday, February 19), the moon is just a day away from its new phase, a time when Luna passes the sun normally above or below the solar disk. That is because its orbital plane is inclined (tilted) to the plane of Earth's orbit by just over five degrees, so most of the time when it passes the sun, it misses Sol. When Luna hides the sun, a solar eclipse occurs, something that will happen on April 20 when the moon's two shadows, the umbra and penumbra, sweep across the Indian Ocean in a rare hybrid eclipse, part annular (ringed) and mostly total. No part of this eclipse will be visible from the US. * Virtually all of the observations in this StarWatch blog can be made with eyes that are unaided, but if you own binoculars, use them. Their greater light-gathering ability will allow for an increase in color saturation which will make these observations easier to view.
Sunday, Feb. 19: The moon is at perigee, its closest position from the Earth, where it will be a mere 222,200 miles in distance. Monday, Feb. 20: The moon is new and is too close to the sun to be seen. The hemisphere of the moon that is never observed from the Earth, the far side, is now in full sunlight. There is no "dark side of the moon" unless you know something about Pink Floyd. All locations on the moon go through a day and night cycle. Luna also rises and sets about the same time as the sun.
Tuesday, Feb 21: Look for a four percent sunlit, razor thin, waxing (growing) crescent moon visible low in the sky around 6:45 p.m. You'll need a good western horizon to make this observation, but it will be worth the effort. Above the moon will be Venus (brighter), and above it, Jupiter. Over the next several days, observers should also be able to witness earthshine, sunlight reflected from a nearly full Earth which reflects off the moon and back to us, allowing viewers to see the region of the moon's surface that is not in direct sunlight. Romantically, it is also called the old moon in the new moon's arms.
Wednesday, Feb. 22: The eastern limb (right side) of the moon is positioned just over one degree from Jupiter, a splendid visual sight in the darkening heavens, or wait an hour until 7:45 p.m. and see it in a completely dark sky. Binoculars, if held steadily enough and properly focused, should reveal two of the four Galilean satellites near the planet, Callisto below Jupiter and Ganymede above the Jovian world. Both are larger than the Earth's moon.
Thursday through Saturday, Feb. 23-25: The moon continues to wax but enters an area of the sky which is populated by fainter stars. Notice how rapidly Luna gains altitude from one evening to the next. That is because its orbit in late winter and the spring is inclined at its steepest angle to the horizon. This is the time of the "smiley moon." As Luna gets closer to the horizon, its crescent shape looks more like the grin of a jack-o-lantern, minus its two eyes.
Sunday, Feb. 26: Place a finger over Luna to cut back on its brightness. Below and to the right, you will notice the gossamer Pleiades or Seven Sisters, the best example of an open star cluster in the heavens. To the left of Luna, you should perceive orangey Aldebaran, the brightest star of the V-shaped head of Taurus the Bull. The "V" is a great binocular target too, and except for Aldebaran, an open cluster in itself known as the Hyades.
Monday, Feb. 27: The moon is at first quarter, half on and half off, with its light to the right and very near to the planet Mars this evening.
Follow the Moon continues next week as Luna heads from first quarter along its orbital path towards its full phase on March 7. Ad Astra!

1384 FEBRUARY 26, 2023: Follow the Moon to Its Full Phase: One of the biggest misunderstandings that my students believe involves the causes of the moon's phases. I would estimate that at least 40 percent of my learners believe that they result from our nearest natural neighbor in space going in and out of the Earth's shadow. That is the concept of a lunar eclipse. Even from where the moon gets its light, the sun, and the process by which the moon shines, reflected sunlight, is sometimes elusive. * Do not think that this is just a Moravian issue because Harvard University began alerting educators about these matters in the mid-1990s and produced a Misconceptions Quiz which I revised for my high school students because of its simplicity. I still use it in my astronomy classes today. * As the moon revolves around the Earth, we observe the hemisphere facing in our direction going through its day and night cycle, a process that takes about 29.53 days. That's it; the phases represent the moon's day and night cycle. Just in case you are wondering, my Moravian students do better than Harvard learners, which on average, got only one to two questions correct when they took the quiz. Go here if you would like to see or take the quiz. Find the correct answers and pictures from last week below this blog. This week, we will follow the waxing gibbous moon as its near side facing us grows into its full phase, completely illuminated by sunlight. Because binoculars gather a greater amount of light than the human eye, they will produce more vivid views, but are not necessary for successful observations.
Sunday, Feb. 26: About two hours after sundown, you will find the moon in the south. Place a finger over Luna to shield its brightness. Below and to the right, you will notice the misty looking Pleiades or Seven Sisters. To the left of Luna, you should witness orangey Aldebaran, the brightest star of the V-shaped head of Taurus the Bull. Except for Aldebaran, the "V" is a great binocular target and a star cluster called the Hyades.
Monday, Feb. 27: Early in the day, the moon reaches first quarter, half on and half off, with its light to the right. By evening its terminator, the demarcation where night is changing into day, has already become slightly gibbous (bulging). That bright, reddish star-like object just above the moon is the planet Mars, about four lunar diameters away in angular distance.
Tuesday, Feb. 28: The waxing gibbous moon is high above the constellation of Orion the Hunter and still relatively close to Mars, now located to the moon's right. Orion is often identified by its three belt stars which are nearly equal in brightness and form a straight line. In South America they are called the three Marys.
Wednesday, March 1: Forget about the moon tonight. Venus (brighter) and Jupiter are within one lunar diameter of each other, in the west after sundown, the best conjunction of the year.
Thursday, March 2: Notice how the moon has exploded in brightness. On this evening at 8 p.m., Luna is positioned just under two degrees below Pollux, the brightest star of the Gemini Twins. You may have to hide Luna with a piece of cardboard or use binoculars to see Pollux. If you can shade yourself from streetlights, you will notice the moon casting distinct shadows on the ground. My grandfather would read the German newspaper by the light of the gibbous moon when he fought on the Russian front during WWI. Try reading a book or magazine by the light of the moon near its full phase. You'll be surprised by the moon's brilliance.
Sunday, March 5: Looking east at 9 p.m., the fat waxing gibbous moon sits equidistant between the brightest and second brightest stars of Leo the Lion. Regulus (brighter) is to the moon's right while Algieba is to Luna's left. Hide the moon with a finger to more easily see these stars or use binoculars.
Tuesday, March 7: The moon is in opposition to the sun tonight, in its full phase, rising when the sun sets and setting when the sun rises. It will be visible all night long. Enjoy the experience that is the moon. Ad Astra!
Harvard Misconception Quiz Answers: 1)c, 2)a, 3)a, 4)d, 5)d, 6)f, 7)d, 8)b, 9)c. 10)a, 11)b