Full Thunder Moon and penumbral lunar eclipse. (Chris Vaughan, Starry Night Education)

This Week’s Sky: June 29 to July 5, 2020

Look for a full Moon and a penumbral lunar eclipse while it forms a triangle with Jupiter and Saturn July 5.

Wednesday, July 1 all night – Jupiter passes Pluto

Jupiter passes Pluto (Chris Vaughan, Starry Night Education)

On the nights surrounding Wednesday, July 1, the faster orbit of Jupiter will carry it closely past distant and slower-moving Pluto. While the faint, magnitude 14.25 dwarf planet is not observable visually in amateur telescopes (red circle), nearby Jupiter will show amateur skywatchers where it is — less than a finger’s width below (or 42 arc-minutes to the celestial south of) Jupiter. Since Earth will be passing Jupiter and Pluto “on the inside track” around the Sun, those planets will be moving westward retrograde through the stars of eastern Sagittarius.

Friday, July 3 from 02:34 to 05:32 GMT – Ganymede shadow transit with Great Red Spot

Ganymede shadow transit with Great Red Spot (Chris Vaughan, Starry Night Education)

From time to time, the small, round, black shadows cast by Jupiter’s four Galilean moons and the Great Red Spot can be seen in amateur telescopes as they cross (or transit) the planet’s disk for a few hours. Starting in late evening on Thursday, July 2 and continuing into Friday, July 3, observers in the Americas can see Ganymede’s relatively large shadow traverse the planet, accompanied by the Great Red Spot. Ganymede’s shadow will cross Jupiter’s northern hemisphere between 02:30 and 05:50 GMT. The spot will complete its passage by 05:30 GMT. Owners of larger telescopes can look for Ganymede’s pale disk following behind its shadow. Your telescope’s optics are likely to flip and/or mirror image the view shown here.

Saturday, July 4 at 12:00 GMT – Earth at aphelion

Earth at aphelion (Chris Vaughan, Starry Night Education)

On Saturday, July 4 at 8 a.m. EDT, or 12:00 GMT, Earth will reach aphelion, its maximum distance from the Sun for this year. The aphelion distance of 94,511,180 miles (152.1 million km) is 1.67 per cent farther from the Sun, than the mean Earth-Sun separation of 92,955,807.3 miles (149,597,870.7 km), which is also defined to be 1 Astronomical Unit (1 AU). Earth’s perihelion (minimum distance from the sun) will occur on January 4.

Sunday, July 5 at 4:44 GMT – Full Thunder Moon and penumbral lunar eclipse

Full Thunder Moon and penumbral lunar eclipse (Chris Vaughan, Starry Night Education)

The Moon will reach its full phase on Sunday, July 5 at 12:44 a.m. EDT, or 4:44 UT. The July full Moon, commonly called the “Buck Moon”, “Thunder Moon” or “Hay Moon”, always shines in or near the stars of Sagittarius or Capricornus.

The Indigenous Ojibwe people of the Great Lakes region call this Moon Abitaa-niibini Giizis, the Halfway Summer Moon or Mskomini Giizis, the Raspberry Moon. The Cree Nation of central Canada calls the June full moon Opaskowipisim, the Feather Moulting Moon (referring to wild water-fowl habits). The Mohawk people call it Ohiarihkó:wa, the Fruits are Ripened Moon.

This full Moon will feature a shallow penumbral lunar eclipse, the first eclipse to be visible in the Western Hemisphere during 2020. The eclipse will begin when the moon contacts Earth’s penumbral shadow at 03:07:23 UT. At greatest eclipse at 04:30:02 UT, only 35 per cent of the Moon will fall within the Earth’s southern penumbral shadow, barely darkening the Moon’s northern limb. The penumbral eclipse will end when the moon exits Earth’s shadow at 05:52:27 UT. The entire eclipse will be visible from all of Central and South America, the southeastern half of North America, and western Africa. The latter stages of the eclipse will be visible in the rest of the USA (except Alaska) and the western Canadian provinces. The rest of Africa and western Europe will see only the early stages. 

Sunday, July 5 all night – Full Moon Jupiter and Saturn form a triangle

Full Moon Jupiter and Saturn form a triangle (Chris Vaughan, Starry Night Education)

When the full Moon rises over the southeastern horizon at dusk on Sunday, July 5, it will form a neat triangle below (or to the celestial south of) bright, white Jupiter and dimmer, yellow-tinted Saturn. The Moon and planets will fit within the field of view of binoculars (red circle) and will produce a lovely wide field photograph when composed with interesting foreground scenery. Over the course of the night, the diurnal rotation of the sky will shift the Moon to the planets’ left, and the Moon’s orbital motion will carry it closer to Saturn than Jupiter.

Monday, July 6 pre-dawn – Venus crosses the Hyades

Venus crosses the Hyades (Chris Vaughan, Starry Night Education)

In the eastern pre-dawn sky between July 3 and 12, Venus’ orbital motion (red path with dates:times) will carry it directly through the Hyades star cluster, the large, triangular grouping of stars that forms the face of Taurus, the bull. Its traverse offers an opportunity to easily see the daily motion of a planet. Look with unaided eyes while the sky is still somewhat dark, around 4:30 a.m. local time — or use binoculars (red circle), which will nicely frame the planet and the cluster’s stars surrounding it.

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 AstroGeo.ca to tour the universe together.