#astronomy See prime-time Neptune’s shut encounter with star φ Aquarii on 6 September – Astronomy Now

September 2, 2019 - Comment

This wide-field finder chart for Neptune depicts a quadrant of the sky centred on the south-southeast as seen from the center of the British Isles round 1am BST firstly of September 2019, or by 11pm BST on the finish of the month. The outermost planet lies near the magnitude +four.2 naked-eye star phi (φ) Aquarii all through the month


This wide-field finder chart for Neptune depicts a quadrant of the sky centred on the south-southeast as seen from the center of the British Isles round 1am BST firstly of September 2019, or by 11pm BST on the finish of the month. The outermost planet lies near the magnitude +four.2 naked-eye star phi (φ) Aquarii all through the month (passing very near it on 6 September). You possibly can find φ Aquarii close to the mid-point of a line drawn between the western aspect of the ‘Sq. of Pegasus’ and first-magnitude star Fomalhaut low within the south. See beneath for an in depth finder chart for Neptune. AN graphic by Ade Ashford.When Uranus was discovered to be drifting from its predicted orbit within the early 19th century, astronomers reasoned that the gravitational affect of a distant undiscovered planet was pulling it out of line. Therefore Neptune was the primary planet to be situated mathematically from the calculations of John Sofa Adams in England and Urbain Jean Joseph Le Verrier in France.

This composite image exhibits the relative sizes of Earth and Neptune. The Voyager 2 spacecraft imaged the planet’s Nice Darkish Spot in 1989, an anticyclonic storm with winds speeds measured as much as 2,400 kilometres (1,500 miles) an hour — the quickest within the Photo voltaic System. Neptune completes a revolution in 16.11 hours. Picture credit score: NASA/JPL.Neptune was finally discovered only a diploma away from its predicted place within the constellation of Aquarius on 24 September 1846 by Johann Gottfried Galle with the help of Heinrich Louis d’Arrest on the Berlin Observatory. Curiously, Galileo was really the primary particular person to watch Neptune, however he mistook it for a background star in observations of Jupiter from December 1612 and January 1613.

We now know that Neptune is a gasoline big virtually 4 occasions the diameter of Earth that lies 30 occasions additional away from the Solar than we’re. At such an unlimited distance, the outermost recognized planet takes virtually 165 years to orbit the Solar.

Neptune reaches opposition on 10 September this yr, having returned to its discovery constellation of Aquarius. On this date Neptune is highest within the southern sky of the UK round 1am BST, some 30 levels (or three spans of a fist held at arm’s size) above the horizon.

Whereas Neptune lies reverse the Solar on 10 September, it’s closest to Earth at 11h UT the day gone by when the least distance between our two worlds for 2019 is 28.928 astronomical items or four,328 million kilometres (2,689 million miles).

Neptune’s huge distance signifies that it solely attains magnitude +7.eight this yr. Therefore it’s too faint to see with the bare eye, however effectively throughout the attain of a pair of binoculars from a darkish sky web site.This graphic exhibits a zoomed-in view of the Neptune finder chart on the high of the web page, targeted on the area of phi (φ), lambda (λ) and the three psi (ψ) Aquarii stars. It depicts subject stars to magnitude +9, in regards to the restrict of a 10×50 binocular below darkish, moonless skies. The pink scale bar exhibits the width of a 10×50 binocular subject of view. Neptune’s retrograde movement by the constellation of Aquarius over the course of two months at five-day intervals is proven. Notice that the outer planet passes simply 13¼ arcseconds – a couple of third of Jupiter’s obvious measurement at opposition – southeast of φ Aquarii on 6 September. AN graphic by Ade Ashford.Neptune is just not troublesome to search out with a star chart just like the one on the high of the web page and its zoomed-in binocular view above, significantly when the planet’s retrograde (east-to-west) movement carries it very near a handy naked-eye information star known as phi (φ) Aquarii on 6 and seven September.

Phi Aquarii shines at magnitude +four.2 and lies simply 13¼ arcseconds northwest of Neptune at 12:36 UTC on 6 September, which signifies that antipodean observers will get the very best views of the pair at their closest.

For observers in Western Europe, Neptune lies virtually 48 arcseconds – in regards to the angular measurement of Jupiter at opposition – east of φ Aquarii at 1:30am BST on 6 September. Twenty-four hours later, Neptune has moved to inside 55 arcseconds southwest of the star. By 1 October, the planet nonetheless lies lower than two-thirds of a level west of φ Aquarii, additional aiding Neptune’s identification.



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