The New Moon lets Comet PanSTARRS Persists a Little Longer, and Jupiter sports Red and Black Spots on Wednesday!

Star Walk
6 min readJun 14, 2018
(Above: A simulated image of how Jupiter will look on Wednesday evening, June 13, after dusk in the Great Lakes region. The Great Red Spot will be crossing the planet while Jupiter’s moon Europa will cast its round black shadow on the planet’s northern hemisphere. Your telescope might flip or invert the image.)

Earliest Sunrise of the Year

For observers near 43° north latitude, Friday, June 15 has the earliest sunrise of the year. Although the longest day for the Northern Hemisphere doesn’t occur until next week’s solstice, earliest sunrise always happens several days before it, and latest sunset happens several days after. The latest sunset will occur on June 27. The specific dates depend on your latitude. As a rule of thumb, the earliest sunrise occurs closer to the solstice the farther north you live.

Binocular Comet Update

If you missed last week’s note about comets, it’s here. As I mentioned last week, there is a faint comet that is observable for the next several nights using binoculars and low power telescopes in the hours after midnight. And it will be easier to see because it’s a new moon period. Comet C/2016 M1 (PanSTARRS) is moving southwestward (towards the lower right) below Sagittarius (the Archer).

(Above: The path of Comet C/2016 M1 PanSTARRS during mid-June. Each yellow circle represents 24 hours, with the comet shown at 1 am local time on Monday, June 11, 2018.)

The comet will rise about 11:15 pm local time, and then reach its highest point about 1.6 fist diameters above the southern horizon at about 3 am local time. Dawn will brighten the sky soon after that time. Overnight tonight (early Monday morning), the comet will be positioned 3° (or three finger widths) to the lower right of the medium-brightness star Ascella (aka Zeta Sagittarii), which marks the bottom left corner of the Teapot asterism. By late this week, it will too far south to be seen by mid-northern latitude observers. But if you live far to the south of the Great Lakes, you’ll have an easy time with this comet.

The Moon and Planets

Tomorrow morning (Monday), the moon will appear as a slim, old crescent above the eastern horizon until dawn. You might catch the even slimmer moon on Tuesday morning just before sunrise, but Wednesday afternoon’s New Moon Phase will hide Luna from view until it returns as a young silver sliver sitting low in the western evening sky on Thursday after sunset. That same evening, look for elusive planet Mercury sitting a generous palm’s width (about 8°) to the moon’s right. The best time to see them will be between 9:30 and 9:50 p.m. local time, when the sky will have become sufficiently dark.

(Above: For a short time after sunset on Thursday, June 14, Mercury and the very young moon will appear over the WNW horizon, as shown here at 9:50 pm local time.)

From Friday evening onwards, the moon will wax fuller and climb higher in the western evening sky. During early evening on Saturday, June 16, the young crescent moon will be situated a palm’s width to the upper left of bright Venus. The pair of objects will set together about 11:45 pm local time. Look for the huge open star cluster Messier 44, also known as the Beehive and Praesepe (The Manger), sitting between the moon and Venus in the same binocular field of view.

Our final moon-event for the week occurs in the western sky in late evening on Sunday, June 17. After dusk, the waxing crescent moon will be situated about 4 finger widths to the lower right of Regulus, the brightest star in Leo (the Lion). Both the moon and the star will fit into the field of view of regular binoculars. During the course of the evening, the moon’s eastward orbital motion will carry it towards Regulus. The moon will set about 12:30 am local time. Observers in the Pacific Ocean region will actually see the moon pass within one finger’s width of the star before they set.

Venus continues to hold court in the western evening sky this week while it continues to climb away from the sun. The planet sets at about 11:35 pm local time all week because it is travelling east while the entire sky is shifting west, holding it in place. Venus is gradually growing larger as it moves towards Earth. In a small telescope, it will exhibit a gibbous (76% full) phase.

(Above The brightest planets, Venus and Jupiter bracket the evening sky this week, as shown here at 11 pm local time. Venus, near Gemini, will set in late evening. Look for the lovely double star Zubenelgenubi sitting just below Jupiter all summer.)

This week Jupiter continues to be the bright object you see shining brightly in the southeastern sky after dusk. It will reach its highest elevation (about three fist diameters) above the southern horizon around 10:50 pm local time, and then drop below the southwestern horizon well before the sun rises. Once it’s dark enough, look for the bright star sitting just below Jupiter. That’s Zubenelgenubi, the brightest star in Libra (the Scales). In binoculars or a small telescope, it splits into a closely separated pair of stars.

On Wednesday, June 13, and visible from dusk until 10:36 pm EDT, the little, round, black shadow of Jupiter’s moon Europa will cross (or transit) Jupiter’s disk. On Friday, June 15 between 9:25 and 11:34 pm EDT, the shadow of Jupiter’s moon Io will transit. A reasonable backyard telescope will show the black shadows, but a very good telescope is needed to see the moons themselves. More shadow transits are available in other time zones around the world.

The Great Red Spot (or GRS, for short) takes about three hours to cross Jupiter’s disk. But the planet’s 10-hour rotation period (i.e., its day) means that the spot is only observable from Earth every 2–3 nights. If you’d like to see the GRS, use a medium-sized telescope (or larger). You’ll have your best luck on evenings with steady air — when the stars are not twinkling too much. The best times to try this week are: Sunday, June 10 at 11:44 pm, Wednesday, June 13 at 9:14 pm (with a Europa shadow transit bonus!), and Friday, June 15 at 10:52 pm. All times are given in Eastern Daylight Time (EDT), so adjust for your local time zone. Try to look within an hour before or after the times I’ve given.

Yellow-tinted Saturn will be rising in the southeastern sky just before 10 pm local time this week. It will spend the summer of 2018 near the Milky Way, just above the Teapot-shaped stars that form Sagittarius (the Archer). Saturn moves over the southern horizon, it’s highest point in the sky, after 2 am local time. It will remain visible until about 5 am local time, when it will sit about 1.5 fist widths above the southwestern horizon. People are often surprised to hear that even a very small telescope can display the planet’s bright, icy rings. Try it! Saturn’s largest and brightest moon, Titan, will spend all this week positioned to the lower left of the planet. (Remember that your telescope might flip the view around.)

(Above: While Jupiter is already visible in the evening sky this week, Saturn joins it after mid-evening, and Mars begins to rise before midnight at the end of this week! The sky is shown here for June 11 at 1 am local time.)

The Summer of Mars starts this week! Starting this Friday, the Red Planet will begin to rise in the east before midnight. Mars, already noticeably brighter than Saturn, will continue to steadily brighten and increase in apparent size as the Earth’s faster orbit brings us closer to the red planet. (We will pass it on the “inside track” in late July.) In the meantime, look for bright reddish Mars shining over the southern horizon just before dawn.

This week, Mercury begins to swing east of the sun, allowing it to be seen low over the northwestern horizon for a brief period after sunset. It will become easier to spot later this week — with the best time being around 9:45 pm local time. While Mercury will spend the rest of June increasing its separation from the sun, Earth’s tilted axis will pull the evening ecliptic, and all the planets’ orbits, lower over the next couple of months, so our prime Mercury viewing time is sooner rather than later.

Distant blue Neptune, among the modest stars of Aquarius (the Water-bearer), is observable in telescopes in the pre-dawn eastern sky after it rises around 1:30 am local time. Uranus is in Pisces (the Fishes).

Astronomy Skylights for this week (from June 10th, 2018) by Chris Vaughan. Keep looking up to enjoy the sky! I love getting questions so, if you have any, send me a note.



Star Walk

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