Cosmic Ladder: Step 2 - The Solar System
Yesterday we began our climb up the cosmic ladder on Earth. Next we move out to the edge of our Solar System, home to note only the planets but an asteroid belt between the orbits of Mars and Jupiter and numerous comets, some of which are on such wide orbits that they technically leave the Solar System only to come around again centuries later.
This is about as far as we can go before we have to use special distance measurements to describe the vast distances in space. When a photon of light leaves the sun, it takes 250 minutes to reach the boundary of our Solar System, a little over four hours.
From our vantage point on Earth, all of the planets along with the Sun and Moon appear to move along an invisible line in the sky called the ‘ecliptic.’ This is because all of the planets in the Solar System move in roughly the same plane in their elliptical orbits around the Sun, and round orbits viewed from edge on look like a line. A quick way to orient yourself to the ecliptic is to note where the Sun rises and sets and draw a straight line from these two points, this is the path that the planets and Moon will be along.
Want to see the planets? It’s possible to view five in a single night. Mercury is visible immediately after sunset a few degrees above the Sun. Venus rises at 4:40 am and precedes the Sun by a few degrees as well, look for it in the pre-dawn twilight. Mars, Jupiter and Saturn all shine brightly in the Southern sky to the West of the Moon after 2:00 am, you can see these three in addition to Venus if you plan to look around 4:30 am.
To get accurate rise times and charts for the planets, visit https://stellarium-web.org/.
Tomorrow we’re moving beyond the Solar System to our galactic backyard!
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Stay well, and clear skies!