June 24 – Constellations

Evening Highlights:
  • Jupiter is still the brightest object in the night sky at magnitude -1.9 (smaller number means brighter), find it in the western sky.
  • Mars is the second brightest object in the southern sky at magnitude -1.54, and is almost directly south.
  • Ringed Saturn is the dimmest of the planets at magnitude 0.12, and can be seen almost directly above Antares (the heart of Scorpius the scorpion) to the south.
  • Learn the major constellations of the night sky, such as the Big Dipper/Ursa Major, Little Dipper/Ursa Minor, Scorpius, Sagittarius and Cassiopeia, and and how to find them.
  • Video: TBD.  Starts at 8:45PM.
  • Presentation: Following the video, Jim will present how to find the common summer constellations using a planisphere, using markers to hop between constellations, and software that can help locate constellations throughout the year.

Mars is one of the four terrestrial planets, which also includes Mercury, Venus, and Earth, and are so-called because they have similar characteristics such as being small, rocky and slowly rotating.  In contrast, Jupiter and Saturn are called gas giants, meaning they’re mostly comprised of hydrogen and helium.  However, don’t be tricked into thinking you could fly through them like the air we breathe!  Gravity is at work, and as you descend below the beautiful clouds of Jupiter and Saturn, gravity compresses the gases to the point where they turn into liquids, further towards the center they become metals, and at the core – well, we really don’t know what exists at the core because we don’t understand the properties of materials at such high temperature and pressure.  The planets are growing more dim as the summer progresses, and Jupiter is slowly descending towards the western horizon, finally disappearing in early August.

The constellations have a very long history, and were already part of the historical record in 4000 B.C., but each culture and region sees different patterns in the night sky and many variations have existed over the eons. However, in 1922, the International Astronomical Union defined 88 ‘modern’ constellations and their boundaries, and are what are commonly used by astronomers today.

Presentation Links

Stellarium: http://www.stellarium.org
Sky Safari: http://skysafariastronomy.com
Kepler Star Wheel (Planisphere): http://kepler.nasa.gov/education/starwheel/

Tonight’s Images

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