As April begins, a waxing gibbous moon rises before sunset, finishing its three-day journey through the constellation Leo. By the 2nd, the moon will have entered Virgo, where it reaches its opposition to the Sun on April 4.
This month's full moon – variously known as the Egg Moon, Pink Moon, Sprouting Grass Moon, Fish Moon, Seed Moon, and Awakening Moon – is also a total lunar eclipse. While the solar eclipse on March 20 was visible from Northern Europe, the second of the paired eclipses, the lunar eclipse, will be visible in the United States before dawn on Saturday.
Whether or not you see all of this very short eclipse will depend, as usual, on location and weather. The full moon begins to move into the Earth's penumbral shadow at 6:16 am in the Eastern time zone, so the moon will have set before the moon is fully eclipsed at 8 am. Viewers in the western part of the US – from the Dakotas, Nebraska, Kansas, and Texas onward – will have the best chance to see the moon fully eclipsed (in the Central Time Zone at 7 am, 6 am MDT, 5 am PDT). Residents of East Asia, Australia, and New Zealand can see it after sunset.
By the time the moon rises in the east the evening of April 4, the moon will no longer be considered "full," an astronomical term to indicate its exact opposition to the Sun. But it will look look plenty big as it rises on the first night of Passover with Spica, Virgo's white-blue alpha star.
The waning moon in the first part of the month gives stargazers an opportunity to watch a very bright Venus in the western sky after sunset. On April 7th, she moves away from the faint constellation Aries into Taurus, and for the next week closes in on the star cluster Pleiades. A moon-lit night can make this beautiful clustering of stars difficult to spot, so as the waning moon rises later, use this opportunity to spot the Pleiades, especially as it will come in useful at the beginning of May when the planet closest to the Sun, Mercury, alights next to them. Venus and the Pleiades are closest on April 11th.
The sky at nightfall on the 21st of April. A slender crescent moon shows low in the west with Venus and the Pleiades
A new moon on April 18 means that a slender crescent moon will show itself low in the west within the following few days. With a good sight line (and clear skies) on the 19th, you might catch that crescent moon with Mars. But if you miss that union, the next few evenings will give you a glorious sight of the moon with Venus and the stars of Taurus. The evening of the 21st promises an especially lovely gathering with the moon, Venus, and Taurus's alpha star Aldebaran.
And as the days finally warm, the first meteor showers of the season arrive. Anytime between April 21 and 23, the Lyriad meteor showers should be streaking across the night sky. Conventional wisdom is that the best time to view these showers is before dawn, since their radiant – the celestial spot through which their parent comet Thatcher is traveling – is the constellation Lyra. Lyra isn't high enough in the sky until close to midnight, so meteors could be too low to see until the early morning hours. Keep in mind, however, that meteors can make their appearance anywhere in the night sky at anytime. The Lyriads' peak is expected before dawn on April 22nd. Look for the bright star Vega, the fifth-brightest star and alpha star of Lyra, high in the sky before dawn.
On April 25, the first quarter moon meets up with Jupiter, still traveling with the faint stars of the Crab, but now inching its way toward the constellation of Leo. On the 27th, the bright star next to the waxing gibbous moon will be Regulus, Leo's alpha star.
Finally, the end of April and the beginning of May provide an opportunity to see a rarely-sighted Mercury. This planet usually travels too close to the Sun to view without a telescope, but the first two weeks of May, Northern Hemisphere skywatchers have a chance to spot the elusive planet hanging out with the Pleiades in the west for almost 45 minutes following the beginning of nautical twilight. With Mars now gone from the night sky, Mercury takes his spot, briefly, on the spring's horizon, with Venus, Jupiter, and Saturn all following in procession in the sky before midnight.