What’s Up in SW Florida’s April Skies
Mars: Evening Planet
This month, Mars is the sole evening planet for most of the month, appearing about 35 degrees above your western horizon after sunset. As you can see from the image, it’s similar in color to the nearby red giants/supergiants, Aldebaran (red eye of Taurus the bull, about 7 degrees eastward from Mars) and Betelgeuse (red raised shoulder of Orion the hunter, higher and farther east). The cute cluster of stars to the west of Mars is the Pleiades (aka the seven sisters), also in the constellation of Taurus. In the western sky on the evening of Monday, April 8, the waxing crescent moon will make a triangle with Mars and Aldebaran, below and to the east of Mars about 7 degrees away. The next evening (April 9), the moon’s rapid orbital motion will have moved it to the upper right, above Aldebaran! This is one of the easiest ways to see how fast the Moon moves against the background stars in our night sky: slow for a person standing and watching, but fast from night to night!
The Brightest Stars
Panning left (eastward), you’ll encounter a really big arc of really bright stars when you’re facing South (still just after sunset). Sirius, brightest star in the night sky, is the middle star of the arc. It represents the hunter Orion’s big hunting dog (Sirius was his name, and is the name of the brightest star in Canis Major, the Big Dog). Canis Major really looks a lot like a big hunting hound, facing toward Orion (and the star Sirius is lined up with but considerably to the east of Orion’s three belt stars). Above Sirius and slightly to the left (east) is his faithful partner, the “other” dog star, Procyon. Procyon is the brightest star in Canis Minor, the Little Dog, and there are only two bright stars making that linear constellation: Canis Minor is a cosmic Dachshund, if you will. Now for the unusual part: below Sirius, there is a third bright star in the arc: Canopus, the second-brightest star in the night sky. It’s the brightest star in the southern constellation of Carina, but many people in the United States don’t get to see it — they are too far north. Here in SW Florida we get one of the best views of Canopus in the continental US. For science fiction fans: it was also the central star of the exoplanet system that included the desert planet Arrakis in Frank Herbert’s “Dune” series. So, although our weather might be warming up soon, remember, you live in one of the best places in the US to see almost all of the night sky at some point through the year! You can see everything but a small circle around the south celestial pole, 26.5 degrees in radius (our latitude), and at our latitude at the right time of night/year you can *just* see all four stars of the southern cross (this month that’s directly above/at your southern horizon about 1 a.m.).
The Other Planets: Predawn Arc, Jupiter in Retrograde
Earth orbits slower than Mercury or Venus (which are closer to the Sun, so farther down the Sun’s “gravity well,” so they orbit quickly), but we are faster than Mars or Jupiter or Saturn, so at times we “lap them” in our orbit, causing them to appear to make a “backward or westward” excursion (or loop) against the background stars. On April 10th, Jupiter will begin to show that westward excursion as Earth’s orbital motion starts to lap the gas giant planet: this is called Jupiter going into retrograde. That retrograde loop of Jupiter’s will last until early August. Jupiter rises just a bit after midnight most of the month. It is sitting in front of the brightest part of the Milky Way and just to the east of the beautiful red giant star Antares. Antares represents the red heart of Scorpius the scorpion, a “curly J shape” you will be able to see SE-S-SW for most of the night. However, early risers have a big advantage again this month: the best time to see the largest number of planets is right before dawn. Early in April, Mercury and Venus are lined up above the eastern horizon around 6 am, and in a big arc upward and southward from them, Saturn and Jupiter show us the plane of the solar system. The Moon will wander through those planets later this month, too: on the 23rd it will pass Jupiter in waning gibbous phase, on the 25th it will pass Saturn (nearly 3rd quarter), waning all the way, and on the 30th it will be a thin crescent still to the west and south of Venus and Mercury, as we head into May.
5: New 12: First Quarter 19: Full 26: Last quarter
Lyrid Meteor Shower
Active between April 16 and 28, the show peaks before dawn Monday morning, April 22 and before dawn Tuesday morning, April 23. However, there will be very few of these meteors visible because of the waning gibbous moon making the sky fairly bright near the origination direction of these meteors. They are caused by debris from Comet Thatcher.
Eta Aquarid Meteor Shower
The Eta Aquarids are a meteor shower made up of little chunks of cometary debris left trailing along in the orbit of Halley’s Comet. The shower is visible from about April 19 to about May 28, with peak activity on May 5. To look for eta Aquarids, gaze ESE anytime after 1 am and before dawn. Just before dawn they will be appearing to radiate from a position about 38 degrees above your SE horizon. Peak activity is only about 55 meteors/hr, and a dark sky is better (if you feel like being up at 4 am)!
New Weekend Morning Planetarium Shows for Kids
This month we have added a special children’s planetarium show at 11:15 on Saturdays and Sundays. And of course there’s the wonderful new meteorite exhibit from Tim Heitz in our lobby (near the Mars meteorite). See you soon at the Center!
— Heather Preston, Planetarium Director