![]() But Brown doesn't think his discovery, or even Pluto, should qualify as a true planet.īrown said the proposal – that a planet is basically anything round orbiting the sun – is too broad and amounts to “No Ice Ball Left Behind,” cheapening the solar system. ![]() ![]() Michael Brown, an astronomer at the California Institute of Technology in Pasadena, Calif., helped lead astronomers to rethink their definition of a planet through his discovery of an icy rock bigger than Pluto. Pluto would keep its planethood while three other bodies would be added, including Pluto’s moon Charon, the asteroid Ceres and Brown’s object 2003 UB313, which he nicknamed Xena. Under the proposed definition, an object is a planet if it is at least 500 miles in diameter, orbits the sun and has a mass at least about one-12,000th that of Earth. Last week, a high-ranking panel from the International Astronomical Union proposed that the solar system be expanded to 12 planets from the current nine, the first attempt at creating a scientific definition for planets. Probably they also couldn’t stomach the criticism that would follow.” On his Web site, the California Institute of Technology astronomer muses about why Pluto has kept its title for so long: “I think that astronomers are as sentimental as the rest of the world and couldn’t stomach removing Pluto. But Brown doesn’t think his discovery – or even Pluto, which was spotted in 1930 – should qualify as true planets. It was Brown’s discovery of an icy rock bigger than Pluto that helped lead astronomers to rethink their definition of what a planet is. “This definition takes the magic out of the solar system.” “When I was a kid, planets were special,” he said. He’s spotted more than a dozen objects that might qualify as planets. ? Few planet hunters stand to gain as much as Michael Brown if our solar system balloons to 12 planets under a new definition. On my roof, the slope is 21 degrees.Pasadena, Calif. Place the phone flat on the board, then read the degree angle shown on the screen this is your roof’s slope. Place a flat board on the roof (where the panels would go) so it spans up-and-down across several shingles. To measure your roof’s slope, open the level app on your smartphone (on an iPhone, open the compass app, then swipe over for the level). All you have to do is plug in three new values on the SYSTEM INFO page: The 10-minute estimate is much more accurate, but it’s still very easy. Later, I’ll explain how to play around with different sizes to see how large your system would need to be to meet your household demand. There’s also a default value for system size, which basically translates into how many solar panels you need. These are set for standard systems on rooftops with arbitrary values for roof slope (called “tilt”) and the direction the rooftop faces (called “azimuth”). Second, the kWh number you found in the two-minute estimate is based on default values on the PVWatts SYSTEM INFO page. To learn what your household electricity usage is, look at a year’s worth of utility bills or check your online utility account most track month-to-month usage throughout the year. If your household is eco-minded, your usage may be well below that average. The average household electricity use in the United States is about 11,000 kWh per year, or about 917 kWh per month. If you run a 10-watt light bulb for 100 hours, you use 1 kilowatt-hour of energy. A kilowatt-hour is an amount of electrical energy equivalent to 1,000 watts used over one hour. First, “kWh/Year” stands for kilowatt-hours per year. Now, you need to understand a few things to know what this means, and why it’s worth it to move on to the slightly more detailed calculation. In all, there are nine factors you can enter to fine-tune your PVWatts calculation, but for first-timers, all you need is your home’s address and a few simple measurements to get a pretty darned good estimate of your home’s solar potential. PVWatts also takes into consideration multiple site factors, such as the slope of your roof and its position in relation to the path of the sun. And there’s more to it than just weather. The tool uses historical weather data for your area to estimate how much power solar panels would produce for you on an average annual basis. PVWatts is a free online calculator tool created by the National Renewable Energy Laboratory, or NREL (which happens to be located in a big, sunny field in Golden, Colorado, my hometown). “What magical source can tell me this?” you may wonder. If you have 10 minutes (and a smartphone), you can get a much more accurate estimate of your property’s power potential. If you have a couple of minutes - literally two minutes - you can get a rough estimate of how much solar power you can produce at your house. Photo © Heshphoto, inc., excerpted from Install Your Own Solar Panels
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