Astronomy: The Week Ahead – Sun 31 May to Sat 6 Jun

Astro photography


Sunday May 31

Neptune is at western quadrature this at 05:52. Our chart is a bit earlier, to keep a dark sky. Find it in the southeast, between Fomalhaut in Pisces Australis, and Alpha (A) Aquaraii, Neptune can be hopped to off two naked eye stars, 1 and 2, magnitudes 4.2 and 3.7 respectively

Quadrature is when a planet is precisely between opposition and conjunction. Western quadrature puts a planet in the morning sky, eastern, the evening sky.

Neptune is small, at 2.3 arcseconds, and distinctly blue, at magnitude 7.80.


Monday June 1

Lyra is an easy constellation to identify constellation in the northeast, just as the sky darkens. Its alpha, or brightest, star is Vega, shining at magnitude 0.55, it is the second brightest stars in the northern sky, and fifth brightest overall. Along with Deneb in Cygnus, and Altair (not shown) in Aquila, it forms the Summer Triangle.

Lyra is easy to identify due to Vega’s brilliance, and the notable rectangular shape of the eastern part of the constellation. All four stars in the rectangle are double stars!


Tuesday June 2

The final Full Moon of spring occurred this morning at 09:20 PDT. But the moon will still appear full when it rises tonight in Ophiuchus at 20:30. Your local horizon may make moonrise appear later, if there is an obstruction such as trees, buildings or mountains.

This is the last full moon of spring, and is called the Strawberry Moon, or in Europe, the Rose Moon. At 3821,117 miles from earth, this is almost as distant as the moon can be. So, instead of a “super moon”, can we call it a “midget moon”?


Wednesday June 3

Will this be the last of Jupiter’s double shadow transits of this apparition?

Io’s shadow begins before its dark, at 20:54, and ends at 23:15. Ganymede starts at 21:51 and ends after Jupiter sets, at 01:41 on 6/4.

Grab your telescope and see if you can tell the difference in shadow sizes, and watch how quickly Io’s smaller shadow transits the planet compared to Ganymede’s.

Also, enjoy the nice unaided view of Jupiter and Venus in the darkening western sky.


Thursday June 4

Look to the southwest an hour before sunrise and see Saturn about to set. The planet rises at sunset, and sets at sunrise, having just passed opposition.

Our morning constellation this week is Ophiuchus, directly over the ringed planet. It is large and mostly rectangular, with a nice line of four stars forming its lower boundary in this view. Its brightest, or alpha star is Rasalhague, high atop the constellation, shining at magnitude 2, and only 47 light years from our sun. Ophiuchus contains more globular clusters than any other constellation.


Friday June 5

Venus reached it greatest elongation today at 15:09, PDT. While at its farthest position in the sky from the sun, it forms a stunning pair with Jupiter, our two brightest planets. Nearby Venus is Castor and Pollux in Gemini, and Procyon in Canis Minor. Jupiter is west of Leo’s brightest stars Regulus. Between them, unlabeled, is the dim constellation Cancer.


Saturday June 6

Let’s have some fun with a nice morning double star. On Thursday I mentioned¬†Rasalhague as the alpha star in Ophiuchus. Today, its neighbor in our sky, Rasalgethi, is the alpha star of Hercules. Even their names seem similar.

Rasalgethi can be split in most telescopes, with a separation of 4.6 arcseconds. Its primary component is a variable, ranging from magnitude 3.0 to 4.0, and yellow color. Its companion is a white-yellow dwarf at magnitude 5.4. The pair are about 360 light years away, and appear to shine at magnitude 2.75. If the primary component were placed where our sun is, it would extend past the orbit of Mars.

Happy viewing!