Tuesday evening April 24th the waxing gibbous Moon will be over the southwest horizon at sunset local time. The Moon will be about 3o from the star Regulus in Leo the Lion. Over the northwestern horizon at the same time will be the planet Venus about 3o from the open star cluster the Pleiades.
Venus and the Pleiades will easily fit within the field of view of binoculars.
This week I’m kicking back as ‘they’ say at my brother’s place in Phoenix Arizona. Since my arrival this past weekend the sky has been overcast or very hazy due to strong winds blowing dust and sand. However this evening the skies over Phoenix were clear resulting in this picture of the 2-day young waxing crescent Moon about 5 degrees west from the inner planet Venus as the two set in the west.
All solar orbiting objects will at some point in their respective orbit cross the plane of the ecliptic. The ecliptic is actually the Earth’s orbit around the Sun, however from our perspective on the Earth it appears as if the Sun is moving eastward along the ecliptic.
On April 12th the inner planet Venus will be at its ascending node as it crosses the ecliptic moving north. And the next day, April 13th, Mercury will be at its descending node moving south as it crosses the ecliptic.
Over the next week or so the two inner planets will pass by each other coming the closest on the 19th when the two will be less then 4o from each other. With only casual observation one should notice that both planets are moving with respect to each other, but in opposite directions. Mercury is recently past its eastern elongation and is now moving westward, in retrograde, toward the Sun and inferior conjunction. On the other hand, or orbit, Venus is moving eastward out from a recent superior conjunction, opposite side of the Sun, toward its own respective eastern elongation.
This animated graphic shows Venus and Mercury over a period of several days from March 16th to the 29th of March. The time is set for 7:15 pm CDT and in the first several frames the planets are first shown as they would appear at 7:15 pm, then I added labels, then their respective orbits. To make the animation easier to see I also turned off daylight, and then finally the labels were turned off then back on at the end.
Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.
Sunday evening March 19th the thin 1.5-day young waxing crescent Moon, and the two inner planets, Venus and Mercury, will be over the western horizon about 1 hour after sunset local time. All three will fit within the width of a 7×50 binoculars field of view (about 7o).
On the evenings of March 3rd, 4th, and 5th the two inner planets Mercury and Venus will become visible, but low, over the western horizon shortly after sunset local time. Due to its faster orbital speed Mercury will pass Venus as this animated graphic is showing. At their closest the two will be separated by about 1.5o.
This should make for good viewing with binoculars and for a great photo opportunity. The two are close enough to just barely fit in a 25 mm eyepiece field of view on a 6″ reflector..
Thursday December 21st the planet Saturn will have reached the astronomical coordinates that officially place it at solar conjunction. From our perspective the planet is behind the Sun, or on the opposite side of the Sun from the Earth.
In reality it is not as much as Saturn moving behind the Sun as it is the Sun passing in front of Saturn – or so it seems. As a distant outer planet Saturn moves more slowly around the Sun than the Earth does. One year on Saturn is equal to 29.7 years (10,832 days) on Earth. So in one day Saturn would travel how much of the 360o orbit around the Sun? That would amount to approximately 0.033o each day.
The Sun, in its apparent motion along the ecliptic moves at the rate the Earth is moving which is 0.99o each day. So with the Sun’s apparent motion (0.99o/day) it quickly, relative to Saturn, passes Saturn while both are moving eastward. So with that in mind you could start watching for Saturn to reappear in the morning skies later next month.