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2022, July 17: Morning Moon, Evening Hero High

This stunning image, captured by the NASA/ESA Hubble Space Telescope’s Advanced Camera for Surveys (ACS), shows part of the sky in the constellation of Sagittarius (The Archer). The region is rendered in exquisite detail — deep red and bright blue stars are scattered across the frame, set against a background of thousands of more distant stars and galaxies. Two features are particularly striking: the colors of the stars, and the dramatic crosses that burst from the centers of the brightest bodies.

This stunning image, captured by the NASA/ESA Hubble Space Telescope’s Advanced Camera for Surveys (ACS), shows part of the sky in the constellation of Sagittarius (The Archer). The region is rendered in exquisite detail — deep red and bright blue stars are scattered across the frame, set against a background of thousands of more distant stars and galaxies. Two features are particularly striking: the colours of the stars, and the dramatic crosses that burst from the centres of the brightest bodies. While some of the colours in this frame have been enhanced and tweaked during the process of creating the image from the observational data, different stars do indeed glow in different colours. Stars differ in colour according to their surface temperature: very hot stars are blue or white, while cooler stars are redder. They may be cooler because they are smaller, or because they are very old and have entered the red giant phase, when an old star expands and cools dramatically as its core collapses. The crosses are nothing to do with the stars themselves, and, because Hubble orbits above Earth’s atmosphere, nor are they due to any kind of atmospheric disturbance. They are actually known as diffraction spikes, and are caused by the structure of the telescope itself. Like all big modern telescopes, Hubble uses mirrors to capture light and form images. Its secondary mirror is supported by struts, called telescope spiders, arranged in a cross formation, and they diffract the incoming light. Diffraction is the slight bending of light as it passes near the edge of an object. Every cross in this image is due to a single set of struts within Hubble itself! Whilst the spikes are technically an inaccuracy, many astrophotographers choose to emphasise and celebrate them as a beautiful feature of their images. (NASA)

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July 17, 2022: The gibbous moon is between Jupiter and Saturn this morning.  Morning Star Venus and Mars are farther eastward.  After night falls, Hercules can be seen high in the south.

Chart Caption – 2022, July 17: Before daybreak, the gibbous moon is between Jupiter and Saturn.

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by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 5:31 a.m. CDT; Sunset, 8:23 p.m. CDT.  Check local sources for sunrise and sunset times for your location.

Morning Sky

SUMMARY OF PLANETS IN 2022 MORNING SKY

The bright moon, 82% illuminated, is nearly halfway up in the southern sky between bright Jupiter and Saturn.  This morning the lunar orb is in front of the dim stars of Aquarius.

Bright Jupiter is over halfway up in the south-southeast.  It is slowing before it reverses its direction and begins the illusion of retrograde motion.  Jupiter rises about three hours after sunset and appears in the southern sky during morning twilight.

Look for the star Deneb Kaitos – meaning “the southern branch of the sea monster’s tail” – 20.2° below Jupiter.  On the earliest sky maps it was a frog, rather than being part of the monster.  A second frog, now named Fomalhaut, is lower in the sky than Deneb Kaitos, about 20° below the moon. Today, Fomalhaut means “the mouth of the southern fish.”

Saturn is to the lower right of the lunar orb and about one-third of the way up in the south-southwest.  It is near another “tail star,” Deneb Algedi – “the kid’s tail. Saturn is retrograding in eastern Capricornus and slowly moving by the star.

The Ringed Wonder rises about 90 minutes after sunset and can be seen low in the east-southeastern sky as evening twilight ends.

Through a binocular another star, Nashira – meaning “the lucky dog of the verdant fields at the end of summer” – makes a triangle with Deneb Algedi and Saturn.  Watch Saturn slowly move westward, making an ever-changing triangle with this pair of stars.  It forms a nice isosceles triangle with the two stars on July 30.

During the next few mornings, watch Saturn pass three stars, cataloged as 42 Capricorni (42 Cap on the chart), 44 Capricorni (44 Cap), and 45 Capricorni (45 Cap).

Chart Caption – 2022, July 17: Venus and Mars are in the eastern sky during morning twilight.

Mars, marching eastward in Aries, is less than halfway up in the sky above the east-southeast horizon.  It is not as bright as Jupiter, but it is the brightest “star” in its immediate vicinity.  If you can see Venus, Mars is nearly one-third of the way from Jupiter to the brilliant Morning Star.  It is beginning its long-distance approach to the Pleiades star cluster, over 20° to the lower left of Mars and about one-third of the way up in the east.  Mars passes it in over a month.

Photo Caption – The Pleiades star cluster. (U.S. Naval Observatory)

The Pleiades may initially catch your attention at the corner of your eye.  Many sky watchers can see six stars, or perhaps seven, without an optical assist.  Through a binocular a few dozen are visible. The star cluster is above another more-widely spread cluster, known as the Hyades.

Along with Aldebaran, the Hyades make a sideways “V,” marking the face of Taurus.  Celestial artwork shows Aldebaran as an eye.

Brilliant Venus, less than 10° up in the east northeast and east of the Bull’s horns Elnath and Zeta Tauri (ζ Tau on the chart), is nearly 20° to the lower left of Aldebaran.  Venus is stepping through an edge of Orion for a few days. It moves into Gemini in two mornings.

Venus rises about two hours before sunrise.  Beginning in 10 days, the planet rises one to two minutes later each morning.  The sun seems to be slowly roping Venus back toward its superior conjunction on the far side of the sun during late October.  The planet seems to begin a slow, but consistent, slide into brighter twilight.  Weekly observations show it lower at the same time interval before sunrise.  By early September, Venus is rising only an hour before the sun.

Evening Sky

Photo Caption – Messier 13: The globular cluster in Hercules. (Photo credit: NASA/ESA/Space Telescope Institute)

Step outside about two hours after sunset when evening twilight ends.  Look high in the south.  Slightly to the east is blue-white Vega and topaz Arcturus is farther west.  Hercules and Corona Borealis are between the two stars.

Hercules is nearly overhead, about one-third of the way from Vega to Arcturus. It is so high that you may fall backwards when you look for it.  Lying on the ground makes it easier to see, especially when using a binocular.  The constellation is not bright and a challenge to see from suburban skies and nearly impossible from cities that suffer from outdoor lighting.

The central part of the constellation is known as “The Keystone,” a wedge-shaped group of four stars that makes the Hero’s waist and knees.  He’s upside down.  His head its marked with Rasalgethi – meaning “the kneeler’s head.”

An impressive star cluster can be found on the right side of the Keystone.  It is cataloged as Messier 13 (M13 on the chart), a spectacular globular cluster.  It can be seen from country skies without an optical assist, appearing as a fuzzy star.  In a binocular, it has a cotton ball appearance, but through a telescope, it looks like a pile of gems against the velvet of the night.  Ask your neighborhood sky watcher to show this one to you through their backyard telescope.   Additionally, at this hour, Saturn peers above the east-southeast horizon.

Globular clusters revolve around the center of the galaxy, but they are outside the plane of the Milky Way, unlike stellar bunches like the Pleiades and the Hyades.  They have thousands of stars compared to hundreds from the so-called galactic star clusters.  The globulars also have different chemistries and they seem to be very old.

Another globular is immediately to the west of the reddish star Antares, the Scorpion’s heart, that is low in the south.  Aim your binocular at the star, the globular cluster is immediately to the right.  With a telescope, look at Antares, and then move the scope a little to the right.  With a low-power eyepiece, the cluster appears.

Corona Borealis, the Northern Crown, is farther westward from Hercules.

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