Last Quarter Moon
Last Quarter Moon (Chris Vaughan, Starry Night Education)

This Week’s Sky: April 13 to 19

Jupiter, Saturn and Mars are this week’s night sky showpieces, set for a close encounter with the Moon. There’s another nearby traveller that was predicted to visit in our night skies, Comet 2019 Y4 (ATLAS).

Jupiter, Saturn and Mars are this week’s night sky showpieces, coming in for a close encounter with the Moon. There’s another nearby traveller that was predicted to visit in our night skies, Comet 2019 Y4 (ATLAS).

Tuesday, April 14 at 22:56 GMT – Last Quarter Moon

Last Quarter Moon (Chris Vaughan, Starry Night Education)

The Moon will reach its last quarter phase at 22:56 GMT on Tuesday, April 14. At last quarter, the Moon rises around midnight and remains visible in the southern sky during morning daylight. Last quarter moons are illuminated on the eastern side, towards the pre-dawn sun. At that time of its orbit, the Moon is also positioned ahead of the Earth in our trip around the sun. About 3½ hours later, earth will occupy that same location in space. After this phase, the waning Moon will traverse the final quarter of its orbit around the earth, on the way to New Moon.

Tuesday, April 14 pre-dawn – Waning Moon approaches planets

Waning Moon approaches planets (Chris Vaughan, Starry Night Education)

In the southeastern sky during the hours before sunrise, for four mornings starting on Tuesday, April 14, the waning Moon’s orbital motion from west to east (or right to left as viewed from the Northern Hemisphere) will carry it close past three bright planets: Jupiter, Saturn and Mars. On Tuesday morning, look for the Moon sitting a generous palm’s width to the right (or seven degrees to the celestial west) of bright, white Jupiter, with yellowish Saturn and reddish Mars arrayed to their left. The scene will make a fine wide-field photograph when composed with some interesting landscape scenery.

Wednesday, April 15  pre-dawn – The Moon meets Saturn

The Moon meets Saturn (Chris Vaughan, Starry Night Education)

The old Moon’s trip past the planets will continue on Wednesday, April 15, in the southeastern sky in the hours before sunrise. After 24 hours of travel eastward, the Moon will now sit a few finger widths directly below (or three degrees to the celestial south of) yellowish Saturn, with brighter Jupiter positioned to their upper right (west) and reddish Mars off to their left (east). The arrangement will offer another lovely photo opportunity.

Thursday, April 16 pre-dawn – Crescent Moon near Mars

Crescent Moon near Mars (Chris Vaughan, Starry Night Education)

Visible in the southeastern sky on Thursday morning between 5 a.m. local time and sunrise, the Crescent Moon will jump east to take up a position four finger widths to the lower left (or 3.5 degrees to the celestial southeast) of reddish Mars. Yellowish Saturn and bright, white Jupiter will be positioned a generous fist’s diameter to the upper right of Mars. This will be the third of four consecutive mornings that will offer a fine photo opportunity featuring the moon and bright planets.

Friday, April 17 pre-dawn – Crescent Moon East of three planets

Crescent Moon East of three planets (Chris Vaughan, Starry Night Education)

This month’s visit of the bright planets by the moon concludes on Friday, April 17 with the Crescent Moon positioned 1.3 fist diameters to the lower left (or 13 degrees to the celestial east) of Mars, Saturn, and Jupiter in the southeastern sky before sunrise. The three planets, plus the yet-to-rise Sun, will nicely define the plane of our Solar System across the sky (green line); although the Moon’s five-degree orbital inclination allows it to stray by up to that distance from that plane — in this case, below it. The Moon will be close enough to the planets to warrant yet another wide-field photograph.

Saturday, April 18 all night – Comet Atlas in the northern sky

Comet Atlas in the northern sky (Chris Vaughan, Starry Night Education)

A comet designated c/2019 Y4 (ATLAS) is predicted to become bright enough to see with unaided eyes in May. If this holds true — and comets are notoriously unpredictable — the comet should be observable in binoculars during April, too. The moonless nights surrounding the weekend of Saturday, April 18 are the best in April month for finding it. Once the sky has darkened, face northwest, and sweep your binoculars inside the large triangle formed by the bright star Capella, dimmer Polaris, and the Big Dipper. The comet’s path during April (red line with date:time labels) will be downwards between Capella and Polaris. In binoculars, the comet should appear as faint, fuzzy grey patch, and elongated due to a developed tail (simulated view inset). Once you’ve located it, a backyard telescope might also show a hint of green, a characteristic colour of these icy visitors.

Sunday, April 19 all night – Ursa Major galaxies

Ursa Major galaxies (Chris Vaughan, Starry Night Education)

The Big Dipper is part of a larger constellation, namely Ursa Major, the Big Bear. As a circumpolar constellation, it moves to a location very high in the northern sky in late evening during mid-April, which is ideal for observing the many galaxy showpieces within it. They can be seen through strong binoculars or backyard telescopes on the dark nights surrounding this weekend.

Drawing a line connecting the stars Phecda to Dubhe, and extending it by an amount equal to their separation, brings one to Bode’s Nebula, otherwise known as the galaxies Messiers 81 and 82. M81 is a magnitude 6.9 spiral galaxy oriented not quite face-on to Earth, making it larger and brighter than M82. M82, located half of a degree to the north of M81, is smaller, but bright due its nearly edge-on orientation. Several other dimmer galaxies can be found within a few degrees of Bode’s Nebula.

Chris Vaughan is a science writer, geophysicist, astronomer, planetary scientist and an “outreach RASCal.” He writes Astronomy Skylights, and you can follow him on Twitter at @astrogeoguy. He can also bring his Digital Starlab portable inflatable planetarium to your school or other daytime or evening event. Contact him through to tour the universe together.