Skywatcher's Guide: April and May 2019


Stars and Constellations

In April, the spring sky is now prominent in the east, along with the familiar Big Dipper.  The Big Dipper is high in the northeast, and the two stars at the end of the bowl can be used to find Polaris, our north star.  Also, the handle can be used to "arc to Arcturus", a bright star in the constellation Boötes. Next, Leo the lion is very high in the east, approaching the middle of the sky now, with the constellation Virgo just below.  The winter constellations are also visible, now in the west.  Taurus the bull is getting lower in the west, near Orion the hunter to the west-southwest.  Canis Major (the big dog), along with the bright star Sirius, is also getting low in the southwest.  Gemini the twins is a little higher in the west, along with Auriga the charioteer in the west-northwest and Canis Minor (the little dog) in the southwest.  The winter Milky Way is now getting lower in the west as well.  Far to the south we can see some constellations making up part of Jason's Argo Navis, which we only get to see briefly since it is so far south.  Finally, there is still a small portion of the fall sky still visible just for the first hour or so of the night.  Cassiopeia the queen is in the north-northwest, and Perseus the hero is in the northwest.

In May, the winter constellations are lower in the west, and Orion, Taurus, and Canis Major are already in the process of setting at the beginning of the night, along with Cassiopeia and Perseus to the northwest.  The spring constellations are higher now, and we can see the rest that weren't up this time last month.  Hercules is below Boötes in the east-northeast.  Some of the summer constellations are also getting ready to come up and will be visible a few hours after sunset.

Interesting Stars Visible in April and May (during observatory hours)

Name / Designation Apparent Magnitude
(lower = brighter)
Sirius -1.44 8.6  
Arcturus -0.05 36.7  
Vega 0.03 25  
Capella 0.08 42  
Rigel 0.18 770  
Procyon 0.4 11  
Betelgeuse 0.45 427  
Aldeberan 0.87 65  
Spica 0.98 262  
Pollux 1.16 38  
Deneb 1.25 3230  
Regulus 1.36 77 means "Little King"
Castor 1.58 52  
Polaris 1.97 431  
Algol 2.09 93 variable star
Denebola 2.14 36.2  
Almak 2.1 / 5.0 & 6.3 355  triple star system w/ 64 yr orbit
Albireo 3.2 / 5.8 & 5.1 390 / 380  possibly a triple star system
Eta Cassiopeiae 3.5 / 7.4 19 480 yr orbit

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Solar System

Mercury will be visible before sunrise during mid-late April, but will be passing behind the sun in mid-late May.

Venus is still high in the morning sky before sunrise, just slowly decreasing in altitude.

Mars keeps getting lower in the west after sunset, moving through Taurus and Gemini.

Jupiter rises around midnight in early April, and gets earlier each night.

Saturn rises earlier and earlier each night, coming up before midnight in early May.

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Calendar of Night Sky Events

Date Event
04/02/19 Appulse of Mercury and Neptune. — Separated by 0.4°.
04/05/19 New Moon.
04/09/19 Appulse of Venus and Neptune. — Separated by 0.3°.
04/11/19 Mercury at greatest western elongation. — Visible before sunrise.
04/12/19 First Quarter Moon.
04/16/19 Appulse of Mercury and Venus. — Separated by 4.3°.
04/19/19 Full Moon.
04/22/19 Uranus at conjunction. — Passing behind the sun.
04/22/19 Peak of Lyrids meteor shower.
04/26/19 Last Quarter Moon.
05/01/19 Appulse of Saturn and Pluto. — Separated by 2.7°.
05/04/19 New Moon.
05/07/19 Peak of Eta Aquariids meteor shower.
05/01/19 Appulse of Mercury and Uranus. — Separated by 1.3°.
05/11/19 First Quarter Moon.
05/18/19 Appulse of Venus and Uranus. — Separated by 1.1°.
05/18/19 Full Moon.
05/21/19 Mercury at superior conjunction. — Passing behind Sun.
05/26/19 Last Quarter Moon.
05/28/19 Ceres at opposition. — Best time to see our nearest dwarf planet.

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Deep Sky

The winter Milky Way is now getting low in the west, but there are still several interesting objects we can see here.  The Pleiades (Seven Sisters, M45) is close to the west-northwest horizon right next to the Hyades (C41), which makes the face of Taurus the bull.  The constellation Auriga is a little bit higher, where we can see M36, M37, and M38, which are visible with binoculars.  The Double Cluster (C14) in Perseus is low in the north-northwest.  Higher in the sky we have the Beehive (Praesepe, M44) in Cancer the crab and Coma Berenices (Bernice's Hair) near the tail of Leo.

We are now beginning to see some globular clusters coming up in the east.  M3 is towards the east, in the constellation Boötes.  Nearby, the famous Hercules Globular (M13) is low to the east-northeast.

For nebulae, we have the spectacular Orion Nebula (M42) now now getting low to the west-southwest. This is the closest star-forming region to our solar system.  We also have some good planetary nebulae, which come from dying stars.  The Eskimo (C39) in Gemini is high in the west, the Owl (M97) in Ursa Major is high in the northeast, and the Ghost of Jupiter (C59) is to the south in the constellation Hydra.

And now the galaxies:  In Ursa Major to the north we have Bode's Galaxy (M81) and the Cigar Galaxy (M82), close enough to be seen together in a low-power telescope.  Nearby in the constellation Canes Venatici we have the Whirlpool (M51), which is a pair of colliding galaxies.  The Pinwheel Galaxy (M101) is also nearby near the handle of the Big Dipper.  Then the Sombrero Galaxy (M104) is in the southeast in the constellation Virgo.

Interesting Deep Sky Objects to Observe during April and May (during observatory hours)

Designation Name Apparent Magnitude Apparent Size Distance
Messier 45 Pleiades 1.6 110' 440 open cluster
Messier 44 Beehive Cluster 3.7 95' 577 open cluster
Messier 42 Orion Nebula 4 85' x 60' 1400-1600 diffuse nebula
Messier 3 (in Canes Venatici) 6.2 18' 34,000 globular cluster
Messier 81 Bode's Galaxy 8.5 21' 1,200,000 spiral galaxy
NGC 3242 Ghost of Jupiter 8.6 25" 1400 planetary nebula
Messier 82 Cigar Galaxy 9.5 14' 1,200,000 galaxy

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Frequently Asked Questions

What's happening in space exploration?

There is so much going on in space that sometimes it is hard to keep up with all the active missions.  We may hear a lot about the big players, but the smaller ones are still out there going silently about their business.  So I will try to give a summary of what is still active.  The dates listed are when they began the current phase of their mission; many of them had previous missions as well.

We'll start with the Sun:  The newest one is the Parker Solar Probe (2019), but we also have SOHO (1996), ACE (1997), WIND (2004), and STEREO (2006).

Mercury does not currently have any active missions, but BepiColombo is en route, expected to arrive in 2025.  Venus also has one:  Akatsuki (2015).

Earth has too many to list, but I'll just mention the one that is not in geocentric orbit:  DSCOVR (2015).  We also have some active lunar missions: LRO (2009), ARTEMIS (2011), Chang'e 4 (2018), and Beresheet (en route, expected to arrive this month).

Mars is next, with Mars Odyssey (2001), Mars Express (2003), MRO (2006), Curiosity (2012), Mangalyaan/MOM (2014), MAVEN (2014), ExoMars TGO (2016), and InSight (2018).

Two asteroids currently have active missions:  Ryugu has Hayabusa 2 (2018) and Bennu has OSIRIS-REx (2018).

Jupiter has one as well:  Juno (2016).  Saturn, Uranus, Neptune, and all the other small bodies in our solar system currently have no active missions.

There are a few deep space probes to mention as well:  Voyager 1 (1980), Voyager 2 (1989), Chang'e 2 (2012), Gaia (2014), and New Horizons (2019).

I think that is all!  This list is always changing, but hopefully it sparks your interest to follow up on some missions you may not have heard of or had forgotten about.

If you have any questions you'd like me to answer in the next issue of SWG, please let me know.  I'm also happy to take suggestions or comments, and also pictures if you'd like to send them.  Happy viewing!

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  • Cornelius, Geoffrey. The Starlore Handbook: an Essential Guide to the Night Sky. San Francisco, CA: Chronicle, 1997. Print.
  • Ottewell, Guy. Astronomical Calendar 2012. Raynham, Mass: Universal Workshop, 2011. Print.
  • Ottewell, Guy. Astronomical Calendar 2013. Raynham, Mass: Universal Workshop, 2012. Print.
  • Ottewell, Guy. The Astronomical Companion. 2nd ed. Raynham, Mass: Universal Workshop, 2010. Print.
  • Astronomy Magazine. February 2013. Volume 41, No 2.
  • Astronomy Magazine. February 2013. Volume 41, No 3.
  • Sky & Telescope. February 2013. Volume 125, No 2.
  • Sky & Telescope. March 2013. Volume 125, No 3.

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