Night Sky Highlights for April-June 2023
By Jim Mazur
There will be a good chance to see elusive Mercury in the early evening sky for the few days surrounding April 11. Mercury will be bright (between magnitude -1 and 0), but so will the twilight sky, so it gets easier to see with each passing minute after sunset as the sky darkens. It will be low in the sky so a good western view is essential.
At about magnitude -4.0, Venus dominates the western sky throughout the spring months. It is bright enough to be seen even before the Sun sets if the sky is clear and you know where to look. Through a telescope, Venus will be in a waning gibbous phase in April and May, then half lit or less during June.
Mars is another bright planet that can be seen in the evening sky throughout the spring. In June, it will be getting closer to Venus, and the two beacons with their contrasting colors should be a striking sight. The crescent Moon joins in a conjunction with Mars and Venus on June 21-22.
Jupiter will be close to the Sun during April, then it will join Saturn in the morning sky in May and June.
Located in Aquarius, Saturn will be visible in the east during the early morning hours this spring.
Except for the first few days of April when Uranus will be below Venus in the evening sky, this planet will be too close to the Sun to observe this spring.
As the spring progresses, Neptune will become visible in the early morning sky in the constellation Pisces. Here is a finder chart for Neptune:
Deep Sky Objects
Springtime offers many galaxies to observe in Virgo, Coma Berenices, Leo, and Ursa Major. But there are also other interesting deep-sky objects, including double stars, globulars, and nearby open clusters. Here are some good targets, along with star-hop charts to help find them.
Globular cluster in Canes Venatici
M3 is one of the brightest globular clusters in the sky, and it can be seen as a fuzzy ball in binoculars. It is a very dense globular, and that makes it a little harder to resolve the individual stars than the more famous M13, but it still is a very impressive object, especially with a big scope. Star-hop chart
Messier 44, the Beehive Cluster
Open cluster in Cancer
This is one of the few open clusters that is visible to the naked eye under a moderately dark sky. It is also one of the closest open clusters, about 610 light years away. It looks like a faint glow in the middle of Cancer, and binoculars or a small telescope will reveal several dozen stars. Star-hop chart
Melotte 111, the Coma Cluster
Open cluster in Coma Berenices
This is another nearby open cluster visible to the naked eye, just 288 light years away. It is a neglected group, probably because light pollution. The roughly 40 stars of this group are spread over a 4.5-degree area of sky. This is an ideal target for binoculars, just about filling the roughly 5-degree field of view of typical binoculars. Star-hop chart
Porrima (Gamma Virginis)
Double star in Virgo
Porrima is easily visible to the naked eye at magnitude 2.7. Through a telescope at high power, it resolves into two stars, one yellow and one blue, making a beautiful sight. The components are only about 3 arcseconds apart so it takes at least 100X to split them. These stars are about 38 light years away and about 34 astronomical units apart. Star-hop chart
Pi and Xi Bootis
Double stars in Bootes
These two nice double stars are just a few degrees apart and not far from Arcturus. Pi Bootis has two white components, magnitudes 4.9 and 5.8, separated by 5.4 arcseconds. The pair is about 320 light years away. Xi Bootis is much closer, 20 light years away, and its blue-white and orange component stars are magnitudes 4.7 and 7.0, separated by 5.3 arcseconds (but the gap is shrinking as they orbit). Both stars of Xi Bootis are smaller and less luminous than our Sun. Star-hop chart
Messier 101, the Pinwheel Galaxy
Spiral galaxy in Ursa Major
M101 is a large face-on spiral galaxy about 21 million light years away. At magnitude 7.7, it can be seen as a faint glow in a small scope, and larger scopes will reveal its bright center, spiral arms, and other details. This is definitely a good target for a dark moonless night. Star-hop chart
Messier 102 (NGC 5866)
Galaxy in Draco
Many purists do not recognize this galaxy as M102 because it is not in the location Charles Messier reported seeing it. There is evidence that what Messier actually saw was a repeat of M101. But NGC 5866 is in the general vicinity and it helps to fill out the list of Messier objects. It is an edge-on lenticular galaxy (one with a large central bulge and tightly wound spiral arms). Star-hop chart
NGC 4435 and 4438, the Eyes
Galaxies in Virgo
Messier did not record these two galaxies, but they are certainly bright enough to see with a small telescope. With moderate aperture, they do look like an eerie pair of eyes staring back at you from deep space. Star-hop chart
NGC 4458 and 4461, in Markarian’s Chain
Galaxies in Virgo
Just about 1/2 degree to the northeast of the Eyes galaxies (see above) is another pair of galaxies, slightly dimmer but still quite visible in a telescope of moderate aperture. Along with the Eyes, these galaxies are part of Markarian’s Chain, an impressive string of galaxies in the heart of the Virgo cluster. If you slew around the area on a dark night, you will probably spot more of them, as shown on the star-hop chart. Star-hop chart