After Sunset
Look high in the north for the Big Dipper. As famous as the Dipper is, it’s not always easily visible from our latitude in Tennessee. During the autumn, it stays hidden near the northern horizon, only to emerge in the wee hours of the morning. But in the spring, the Dipper is high in the sky, easy to find.
You can use the stars of the Big Dipper to find Polaris, the North Star. Use the two stars at the end of the bowl of the Dipper to point you to Polaris. When you face Polaris, you’re facing due north.
Polaris is not a particularly bright star, but it does remain fixed in the sky throughout the night and throughout the year. Polaris is at the end of the handle of the Little Dipper. This group of stars is officially known as Ursa Minor the Little Bear. Similarly, the Big Dipper is just a part of the official constellation Ursa Major the Great Bear. You’ll need dark skies to see the great bear’s fainter stars.
Imagine poking a hole in the bottom of the Dipper to let the water drip out. The water falls onto the back of Leo the Lion. The head and mane of the lion are represented by a group of stars that looks something like a backwards question mark. Other stargazers imagine the top hook of a coat hanger, or a sickle in this group of stars. The “dot” at the bottom of the question mark is Regulus, the brightest star in Leo. It marks the regal heart of the lion.
Follow the curved handle of the Big Dipper to trace the ‘arc’ to Arcturus, the orange colored star in Boötes the Herdsman. Then speed on to Spica, the single bright star in Virgo the Maiden, low in the southeast. Neither of these constellations has any other bright stars. Even under dark skies away from city lights, it’s hard to imagine these mythological figures just by connecting the dots.
Look low to the west for our last glimpses of winter constellations. Orion the Hunter stands out early in the month, but will be lost in the glow of sunset by May. Follow Orion’s belt to the left to find the brightest star in the night sky, Sirius, in Canis Major the Big Dog. Follow the belt stars to the right to find orange star Aldebaran, the eye of Taurus the Bull.
Keep going past Aldebaran in the same direction to find a beautiful cluster of stars known as the Pleiades. To some eyes it looks like a miniature version of the Little Dipper. Under dark skies most people can see six stars, but under excellent dark-sky conditions, people with good eyesight can see seven. With a small telescope or a pair of binoculars, you may see dozens! The Pleiades is an example of an open star cluster. Look for it early in the month - by the end of the month it will set early, lost in the glow of sunset.
Right between the horns of Taurus is the bright planet Jupiter. Take a look at Jupiter through a good backyard telescope and you can see the cloud bands whipped up by the planets fast rotation. Jupiter spins on its axis every ten hours, compared to the 24 hours it takes Earth.
Keep an eye out for Jupiter's four largest moons, visible even through good binoculars. Over the course of several days you can watch the moons shift position as they orbit the giant planet. Look for our own Moon near Jupiter on April 2.
Draw a line from Orion’s blue-colored foot Rigel up through red star Betelgeuse, and keep on going until you run into Gemini the Twins. The bright stars Castor and Pollux mark the heads of the twins from ancient mythology. Under dark skies you may just be able to pick out two stick-figure bodies leading back towards Orion.
At the beginning of the month, you can spot the red planet Mars near Pollux. Mars may only appear like a pale pink dot in the eyepiece of a telescope, but over weeks and months you can watch it as it moves away from Gemini and onward through the constellations. Around the middle of June it will pass very close to Regulus, in Leo the Lion. Look for the Moon near Mars on April 5.
From Dark Skies
Bright outdoor lighting can make it hard to see all but the brightest stars. Even a bright Moon can make it difficult to see the fainter objects in the sky. On a clear night, find a dark spot far away from city lights, give your eyes time to adjust to the dark, and look for even more celestial sights.
Just beneath the belt of Orion is a faint patch of light that marks the hunter’s sword. This is M-42, the Great Orion Nebula. A small telescope can reveal the overall shape of the nebula, as well as a quartet of young stars near the center called the Trapezium. These stars formed out of the gas and dust of the nebula.
Look between the constellations Leo and Gemini to find... nothing? Even under dark skies you’ll have to look closely to spot the famous but faint constellation Cancer the Crab, shaped like an upside-down letter Y. Near the center of the Y is M-44, the Beehive Cluster. Like the Pleiades in Taurus, this open star cluster is a great target for binoculars.
On its way to its mid-June encounter with Regulus, Mars will pass very close to the Beehive over the first few days of May. Point your binoculars at Mars over several nights to track Mars' motion relative to the beautiful star cluster. The Moon will join in, appearing near Mars on May 3.
Early Morning
As Earth orbits the Sun throughout the year, the constellations rise and set just a little bit earlier every day. You won’t see much difference from night to night, but you will over the course of weeks or months. What we see in today’s pre-dawn sky is a preview of the early evening sky in later months. Go out before dawn this month for a look ahead at the summer evening sky.
By morning, our winter constellations have long since set in the west, and even springtime constellation Leo the Lion has set. High in the east are the three bright stars that make up the Summer Triangle. To the south is the J-shaped Scorpius the Scorpion, with the red star Antares.
About an hour before sunrise, look low in the east for a glimpse of brilliant Venus. For an extra challenge, find a clear morning and a location without too many trees, hills, or buildings in the way and you might just glimpse Saturn and Mercury rising just before the glow of sunrise hides them. A very thin crescent Moon will join the group on the morning of April 25.
Before you set your alarm for the wee hours of the morning, consider planning out your observing. Desktop planetarium software like the free, open-source Stellarium can show you more precisely where night sky objects can be found on any date and time, and help you plan ahead.