I have long been intrigued by the Planet Venus. First, it is the brightest natural object we can see in the sky, next to the Moon and the Sun. Second, my possible next novel, The Venus Syndrome, could consume me for the next year.
From the 25August2013 issue of Skywatch by Mike Shanahan (sorry, but can't yet find a link, so the above is from Society of Popular Astronomy):
Since Spica shines at first magnitude and Venus shines at minus 4 magnitude, that means that
Venus is about 100 times brighter than Spica.
I've always wondered what was star magnitude. The concept began in the days of Ptolemy (left) when he and others assigned the sixth magnitude to stars that were barely visible. They just stated that a first magnitude star, like Spica, was 100 times brighter than a sixth magnitude. That was two millennia ago, and the numbers still stand.
Mathematically, a logorithmic scale using 2.512 as the base was implemented. (Note: the common logorithm has a base of 10 and a natural logarithm has a base of e, or 2.7183.) Thus, a 1 magnitude star has:
2.512x2.512x2.2.512x2.512x2.512 = 100
times the brightness of a 6th magnitude (6 minus 1 equals 5, thus the need to multiply 2.51 five times). Using this logic, a 1 magnitude star is 2.512 the brightness of a 2 magnitude.
Here are the magnitudes:
- -26 Sun
- -13 Full Moon
- -7.5 1006 Supernova (right, photo taken by a Benedictine monk...nah, just kidding), the brightest steller event in "recorded" history
- -5.9 International Space Station at brightest
- - 4 Venus (-4.89 under special conditions)
- - 2 Jupiter (also indicated at -3 in some tables)
- - 1 Sirius (maybe as high as -1.47)
- - 1 Moon at total eclipse
- - 1 Hale-Bopp Comet (1997, right)) at peak
- -.27 Alpha Centauri star system
- 0 Vega
- +.5 Sun as seen from Alpha Centauri
- + 1 Saturn
- + 1 Spica
- + 2 stars of Big Dipper
- + 2 Halley's comet (right) in 1986 at peak
- +3 faintest stars from low light environment (rural, suburban)
- + 4 faintest stars from outer suburbs
- + 5 faintest naked-eye stars from dark rural areas
- + 5 faintest naked-eye moons of Jupiter from dark rural areas
- + 6 faintest naked eye stars at least 100 miles from major cities
- + 7 binoculars at least 140 miles from major cities
- + 8 Neptune (right) with binoculars
- +14 Pluto with a large telescope
- +36 Faintest objects to be observable in visible light with the European Extremely Large Telescope (below, which hasn't been built yet, but at a billion dollars, should be operational at the top of Cerro Armazones, Chile in the early 2020's, and will be 30% more powerful than the Thirty Meter Telescope to be built on Mauna Kea, but don't attempt to hold your breath for the TMT)
So on September 4, for example:
There is a New Moon (meaning "no" moon), with Venus and Spica right next to each other in the West after sunset.
But remember that Venus is 100 times brighter than Spica, so some of you might need binoculars to see the star. On September 8:
Venus, Spica and Saturn are low in the Western sky soon after sunset. The crescent moon lies between Venus and Saturn.
Mercury joins those planets towards the end of September.
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