The evening sky is rich.
See the end note about enlarging illustrations.
Mars is on top of the Beehive cluster, anciently known as Praesepe the “manger,” in the middle of the dim constellation Cancer. This nearest of star clusters is also relatively dim and diffuse. It can be glimpsed with the naked eye when higher in a dark sky. Binoculars or telescope will show it overwhelmed by Mars. In the logarithmic scale used in astronomy, the magnitude of the cluster is 3.7 and that of the planet is now 1.8, which means that the light coming to us from Mars is nearly 6 times more.
As the broad arrow on the celestial equator shows, the ornaments of the western sky are slanting downward and, an hour later, Venus will be below the horizon, the Twin stars only about 1° and Mars 4° above it.
The Moon, nearly full, has just risen, away over in the southeast, in Scorpius.
The “antapex of Earth’s way” is the direction away from which we are moving in our orbit. Being roughly 90° from the Sun, it has just passed the September equinox point because the Sun has just passed the June solstice point.
The arrows through the moving bodies, including the Sun, show their movement from 2 days before to 2 days after the time of the picture, in relation to the starry background. You can see that Venus is moving east faster, and Mars slower, than the Sun. Both are beyond the Sun, but Venus is moving out toward its greatest elongation (October 29), whereas from our point of view Mars is falling back toward its conjunction behind the Sun (Oct. 8)
In this space view, the planets’ paths are shown in June; in yellow are sightlines to them from Earth on June 23. The viewpoint is 15° north of the ecliptic plane, and 5 astronomical units (Sun-Earth distances) away from the Sun. The dashed line shows longitude 0°, the vernal equinox direction. The Sun is exaggerated 4 times in size, the four inner planets 300 times.
AltShift3Constellations
Here’s a picture with some pretty colors. More about this later.
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ILLUSTRATIONS in these posts are made with precision but have to be inserted in another format. You may be able to enlarge them on your monitor. One way: right-click, and choose “View image”, then enlarge. Or choose “Copy image”, then put it on your desktop, then open it. On an iPad or phone, use the finger gesture that enlarges (spreading with two fingers, or tapping and dragging with three fingers). Other methods have been suggested, such as dragging the image to the desktop and opening it in other ways.
Sometimes I make improvements or corrections to a post after publishing it. If you click on the title, rather than on ‘Read more’, I think you are sure to see the latest version.
This weblog maintains its right to be about astronomy or anything under the sun.
The Beehive or M44 is fairly with the naked eye in darker skies.i think that you can just make it out on the canopy from smaller city skies without an optical aid although it doesn’t stand out unless you know where to look.
Hello again Mr. Ottewell,
Doing some internet searching, I couldn’t easily find the history for why it made sense to define the vernal (or autumnal maybe, as depicted in the image?) equinox as the solar 0 longitude, could you (or do you) address this in your blog?
Thank you again!
Possibly because the “First Point of Aries” (Vernal Equinox) marks one of two points or “nodes” where the Ecliptic and Celestial Equator intersect. The Vernal Equinox is the sun’s ascending node while the Atumnal Equinox marks the sun’s descending node, with respect to the Celestial Equator.
Hello Mr. Ottewell,
I am unfamiliar with identification methods for the lines of solar longitude, so thank you for including that detail. Is the solar prime meridian aligned with our vernal equinox (per the text), or what appears to be the autumnal equinox on the image, since it is roughly 90 deg ahead of earth as drawn?
Thank you again!
Yes, the vernal equinox point – the point where the ecliptic ascends northward through the celestial equator, or, in a wider solar-system perspective – where the Earth’s celestial equator descends southward through the ecliptic – is the zero point for measurement eastward in ecliptic longitude or equatorial right ascension; and also for measuring north-south in ecliptic latitude and equatorial declination. I think by “the solar prime meridian” you mean either the zero line of ecliptic longitude or the zero line of right ascnesion; both of them run through this point. –Large graphics in my Astronomical Companion make this clearer than words! Tell me if I haven’t answered your question.
The space view of the inner planets was very helpful. Thanks.
Thanks. I’ve been watching Venus adorn some flamboyantly colorful sunsets lately. Now I’ll also keep an eye out for Mars and use my binoculars for the beehive.