July Under Starry Skies

The night skies of this warm summer month would unfold the magnificent mysteries and enchanting enigmas of planets, stars, and constellations that abound awesomely all over the heavens. Fleet-footed planet Mercury is darting through Gemini (the twins) in the punchy vicinity of the sun. Thus, discerning it would be difficult this month. Similarly, the massive planet Jupiter would stay unseen this month. It is too close to the Sun. It is lost in solar glare. It is tumbling through the puny and faint constellation Cancer (the crab). The vibrant planet Venus can be visualised in the western sky for some time after dusk fades to darkness. It is cavorting with blazing stars that sketch in the compelling constellation Leo (lion). It is then dipping down towards the western horizon and becoming evanescent. The red planet Mars can be marvelled at in the eastern sky during dawn before sunrise for a few hours. 

It is marching across and mingling with stars that form the commanding constellation Taurus (bull). The ringed planet Saturn can be sighted in the eastern sky from the wee hours of the night till dawn. It thereafter plunges towards the south-eastern horizon and disappears. It seems like a lambent spot of light in the southern section of the sprawling constellation Pisces (fishes). Planet Uranus can be perceived in the eastern sky for some hours till morning twilight before sun-up. It can be recognised as a sheen speck of light in the constellation Taurus. 

The captivating cryptic Crystal Ball Nebula (NGC 1514) bewitches Taurus. It is 1520 light-years away. It was disclosed by British-German astronomer William Herschel in 1790. Observations by James Webb Space Telescope (JWST) show filamentary and clumpy details. The far-flung planet Neptune could be admired in the eastern sky from midnight till daybreak. It would be ignored by the brightening day-begin. It would be greeting planet fans from the eastern flank of Saturn in the constellation Pisces. These two pleasant planetary duos would be floating fabulously below the amazing circlet asterism of Pisces. 

The new moon is on 14 July. One could explore the conundrums surrounding gloomy galaxies and star clusters because there is no moonlight to meddle with. The full moon would mesmerise moon-lovers on 29 July. 

This full moon is popularly famed as the 'buck full moon' because the male buck deer grow their new antlers at this time of year. The new and full moon traverses tangibly through the comely zodiacal constellations Gemini and Sagittarius (the archer). Our strange but indispensable Sun is sailing smoothly across congenial constellations Gemini and Cancer (the crab). The Delta Aquarids are designated as an average meteor shower that can overwhelm meteor hunters with up to 20 meteors per hour at its maximum moment. The shower runs annually from 12 July to 23 August. It peaks this year on the night of 28 July till the morning of 29 July. Unfortunately, the full moon will obscure most of the streaking stars this year. However patient and ardent onlookers may still optically catch some coruscating ones. It rambles steadily from late July through early August and accompanies even persistent Perseids. The radiant for the Delta Aquariids is located adjacent to the dim star Skat (alias Delta Aquarii), dwelling in the constellation Aquarius (the water bearer). It rises in mid-evening and ascends highest by 02 AM local time. 

It sinks by dawn. It can be spotted above fulgent star Fomalhaut (Yam-masta) that is merely 25 light-years away and residing in confounding constellation Pisces Austrinus (fish’s mouth) and below the western region of the glistening Great Square of Pegasus (winged horse). Baffling binary star Skat is simply 113 light-years away. It is drifting further away from the Sun with a radial velocity of just 17 kilometres per second. The Delta Aquariids’ parent comet stems from the 96P/Machholz Complex. It is a curious collection of eight meteor showers, including Delta Aquariids, plus two comet groups (Marsden and Kracht) and one arcane asteroid (2003 EH1). 

These meteor showers and comets appear to share a common origin. They are all relevantly related to comet 96P/Machholz, which was revealed in 1986, from Loma Prieta Mountain in California. Comet 96P/Machholz encircles the Sun every 5.3 years and gets eight times closer to the Sun than we are. Its perihelion (shortest span) is 0.12 AU. They venture well inside planet Mercury’s trajectory. Scintillating shooting stars can be savoured during moon-free mornings after midnight in the eastern sky even a week before their climax to avoid disturbance by lunar luminescence. The Delta Aquariids are best viewed at pre-dawn away from the glow of city lights. 

The moon, in Capricornus (sea goat), will be two days past full phase at the shower's surge, presenting significant interference throughout the night. Meteor showers arise when the earth passes through streams of debris left behind in the wake of comets and asteroids. Over time, these pieces of grits distribute themselves along the length of the progenitor's path. Sparkling stars are seen whenever one of these particles collides (generally at speeds of 60 kilometres per second) with the earth's atmosphere, typically burning up at astonishing altitudes of 70 to 100 kilometres.

Earth's annual way around the Sun will carry it to its furthest point from the Sun (dubbed its 'aphelion'), lying at a dramatic distance of 1.0166 AU. One astronomical unit (AU) is defined as the mean Sun–Earth span, measuring circa 150 million kilometres. The earth's gap from the sun varies by around three per cent over the course of the year because its track is slightly oval, following a congenial circuit known as an ellipse. However, in reality this variation is rather slight, and the earth's orbit is actually almost circular. 

Earth readily completes one revolution around this trail each year and reaches its greatest length from the Sun on almost the same day every year. In 2026, this day transpires formally on 06 July. Technically speaking, the sun appears to be punier than at any other time of year, and the earth allegedly receives the least radiation. In practice, however, paltry three per cent differences in the earth's distance from the sun are hardly noticeable and could be neglected. 

Annual alterations in our weather, for example, between the hot summer and cold winter, are coherently caused entirely by the tilt of the earth's axis of rotation, rather than by any change in solar distance. The sun at aphelion will be idling in Gemini. Earth's axis is tilted at approximately 23.44 degrees relative to its orbital plane. It is responsible for the seasons and climate zones. Axial tilt (obliquity) is the angle between the earth's rotational axis and the line perpendicular to its orbital plane (ecliptic). It slowly decreases over time due to gravitational interactions with the Sun, moon and other planets. 

This slope causes one hemisphere to lean towards the Sun while the other inclines away, producing seasonal alterations in sunlight and temperature. Over billions of years, the gravitational influence of the moon and sun stabilised the slant, preventing extreme fluctuations. It is crucial for life and climate. It determines seasons and the positions of the Tropics of Cancer and Capricorn and the Arctic and Antarctic Circles. Without it, the equator would obtain constant sunlight year-round and higher latitudes would experience minimal seasonal modification. 

The perplexing dwarf planet 134340 Pluto will reach the so-called opposition on 27 July. It would provide us with optimal time to recon it for much of the night in the constellation Capricornus. It will become accessible above the south-eastern horizon late after dusk and will be aloft by midnight above your southern horizon. 

It becomes unavailable before sunshine when it slips towards the south-western horizon. When any planet is in opposition, it sits on the same side of the Sun as Earth. Even when it is in immediate Earth's proximity, it looks like a polished pinprick of light. It will be a whopping 34.55 AU away. Ferreted out in 1930 by American astronomer Clyde Tombaugh, Pluto was long considered the ninth planet of the solar system. 

It was reclassified to dwarf planet status by the International Astronomical Union (IAU) in 2006. Its orbital period is a staggeringly 247.94 Earth years. Its diameter is 2,376.6 kilometres. Its temperature drops to freezing at minus 232 degrees Celsius. Pluto is proud of its five mystical moons (Charon, Styx, Nix, Kerberos and Hydra) with nomenclatures from Greek mythology. Pluto loiters in the quirky Kuiper Belt, which is a vast, doughnut-shaped area with icy bodies beyond Neptune.

(Dr. Shah is an academician at NAST and patron of NASO.)