For April 2023, the full moon, the Paschal Moon, is on April 6, and sets the next Sunday as Easter. This is the first full moon after the Vernal Equinox. The Last Quarter Moon is on April 13. In the dawn sky, the waning crescent moon passes below Saturn on April 16. New moon is on April 20, and the waxing crescent lies just below brilliant Venus on April 22. The first quarter moon sits just to the right of Mars on April 25. The moon is, again, full as May begins.
Mercury is visible just below Venus on the western horizon the first two weeks of April, with the greatest eastern elongation, 19 degrees from the Sun, happening on April 11, when it will be half lit in our scopes. It fades fast is it laps us in retrograde as a thin crescent.
For a detailed map of northern hemisphere skies, visit skymaps.com.
Yellow Capella, a giant star the same temperature and color as our much smaller Sun, dominates the northwestern sky. It is part of the pentagon on stars making up Auriga, the Charioteer. Several nice binocular Messier open clusters are found in the winter milky way here. East of Auriga, the twins, Castor and Pollux, highlight the Gemini. South of Gemini, Orion is the most familiar winter constellation, dominating the southern sky at dusk. The reddish supergiant Betelguese marks his eastern shoulder, while blue-white supergiant Rigel stands opposite on his west knee. Just south of the belt, hanging like a sword downward, is M-42, the Great Nebula of Orion, an outstanding binocular and telescopic stellar nursery. The bright diamond of four stars that light it up are the trapezium cluster, one of the finest sights in a telescope. In the east are the hunter’s two faithful companions, Canis major and minor. Procyon is the bright star in the little dog, and rises minutes before Sirius, the brightest star in the sky. At eight light years distance, Sirius is the closest star we can easily see with the naked eye from west Florida.
To the southwest, we are losing the constellation Eridanus in the sun’s glare. With it, disappears my favorite galaxy in the sky (except for our home Milky Way, of course). NGC 1300 is a barred spiral galaxy, visible in moderate sized scopes, some 61 million light years distant. I first photographed it with my new eVscope on November 27, and was delighted to see the familiar “S” shape. Then came the news on December 6 that the DLT 40 survey at University of California Davis announced that a magnitude +15.7 supernova had been found between the nucleus and upper spiral arm of the galaxy.
Sarah Fletcher of the EAAA confirmed the exploding star, now designated Supernova 2022 acko, easily imaged with our eVscope. Marc Glover’s image is shown below, one of dozens of local amateur astronomers have participated in taking several images of the fading star every week when clear skies permitted. These have now been cataloged in a new lab on Supernova Light Curves for my RODP ASTR 1020 “Stars and Galaxies” students, downloadable from our Escambia Amateur Astronomers Facebook files. Participate in “Citizen Science” by doing your own plot of the fading of the new (OK, it really happened two million years after the dinosaurs got wiped out by the KT event, and the light just arrived). By determining the shape of this light curve, we can decide if this was a Type I supernova, where the whole white dwarf star was blown completely up, or a Type II core collapse, where the core shrinks into a Pensacola-sized neutron star, such as the famed Crab Nebula, which we will meet later. The first curve comes to a sharp sudden peak but fades rapidly, as only about 1.4 solar masses are blown up. The latter gives an extended and very slow decline, since dozens of solar masses must gradually cool off and spread out. It is this death of massive stars (like Betelguese eventually?) that recycle the “us” stuff back into space.
Overhead near Mars in Taurus is the remains of the most famous recent supernova, M-1, the Crab Nebula. This photo was taken at Big Lagoon with an eVscope March 11. Dr. Andy Walker of the EAAA took this photo, despite occasional clouds disrupting the time exposure several times. This star was seen to explode in July 1054 AD, becoming visible with the naked eyes in broad daylight for weeks. Look closely at the chaotic tendrils of hydrogen, moving fastest and glowing red on the outside of the nebula. Other heavier elements, newly created and liberated from the core of the collapsed supergiant star, glow with their own characteristic colors as well. Now look at the core, and you will see a central star that is no longer one. This is a magnetar, spinning thirty times per second, literally “pumping iron” (the last abundant element formed before the core collapse) and just to the right of it, the arc of the shock wave transferring energy via its strong magnetic field to the glowing, expanding cloud of star stuff.
To the northeast, look for the Big Dipper rising, with the top two stars of the bowl, the pointers, giving you a line to find Polaris, the Pole Star. Look for Mizar-Alcor, a nice naked eye double star, in the bend of the big dipper’s handle. Take the pointers at the front of the dipper’s bowl south instead to the head of Leo, looking much like the profile of the famed Sphinx. The bright star at the Lion’s heart is Regulus, the “regal star.” Now, take the curved handle of the Big Dipper, and follow the arc southeast to bright orange Arcturus, the brightest star of the spring sky. Recent studies of its motion link it to the Sagittarius Dwarf Galaxy, a companion of our Milky Way being tidally disrupted and spilling its stars above and below the plane of the Milky Way, much like dust falling away from a decomposing comet nucleus. So this brightest star of Bootes the Bear Driver is apparently a refugee from another galaxy, but now trapped by our Galaxy’s gravity.
Now spike south to Spica, the blue-white gem in Virgo rising in the southeast. Virgo is home to many galaxies, as we look away from the obscuring gas and dust in the plane of the Milky Way into deep space. To the southwest of Spica is the four sided Crow, Corvus. To the ancient Greeks, Spica was associated with Persephone, daughter of Ceres, goddess of the harvest. She was abducted by her suitor Pluto, carried down to Hades (going to Hell for a honeymoon!) and when Jupiter worked out a compromise between the newlyweds and the angry mother-in-law, the agreement dictated Persephone come back to the earth’s surface for six months of the year and Mama Ceres was again placated and the crops could grow again. As you see Spica rising, it is time to “plant your peas,” and six months from now, when Spica again disappears in the sun’s glare, you need to “get your corn in the crib.”
We have set new dates for our public gazes at Big Lagoon State Park west of Pensacola for these Saturdays: April 8 and 23. Be sure to check in at the gate before sunset. Tentative Pensacola Beach Pavilion stargazes (pavilion near the Beach Ball Water Tower) Friday and Saturday nearest first quarter moon: April 28/29, May 26/27, June 23/24, July 28/29, August 25/26, and September 22/23.
For more information on the Escambia Amateur Astronomers and our local star gazes for the public, visit eaaa.net Gaze info/requests at 291-9334. You can contact our sponsor, Lauren Rogers, at Pensacola State College at lrogers@pensacolastate.edu. Contact Dr. Wayne Wooten at johnwaynewooten@gmail.com.
