On any given night around the world, thousands of people peer into deep space because of John Dobson. An 89-year old with a white ponytail and a knack for comedy, John Dobson revolutionized astronomy. "Possessing a quicksilver wit, a gift for turning a phrase that makes scientific concepts accessible, and an energy that belies his nearly 90 cycles around the sun, Mr. Dobson is one of historyÌs greatest popularizers of science," (Wall Street Journal 9/1/04). He is the inventor of the Dobsonian telescope mount, which changed the field of astronomy dramatically, making telescopes accessible to the public on every continent.

A former Vedanta monk of the Ramakrishna Order, he is a co-founder of "Sidewalk Astronomers," an organization that encourages amateurs to share their telescopes and knowledge with others on busy city streets and in national parks. As John says, "The Universe is bigger than the Earth; it's bigger than the solar system; it's bigger than our galaxy and we owe it to ourselves to notice it." The film follows John as he tours the country from the sidewalks of San Francisco to colleges, universities, astronomy clubs, star parties and to Stellafane, a convention of telescope makers in Vermont. It features sequences on sidewalk astronomy, telescope making, the Moon, Sun, major planets, galaxies, Big Bang Theory, and the nature of time and space. We also get to know John Dobson, a fascinating thinker, philosopher, teacher, and inventor who encourages us to think about the Universe. This astronomical and cosmological journey is illustrated with actual footage and photos of space shot from satellites and spacecraft as well as animation courtesy of NASA, the Jet Propulsion Laboratory, the Goddard Space Flight Center and the Hubble Space Telescope Institute.

The Eye and Dark Adaptation

TO MAXIMISE YOUR SENSITIVITY to dim light you should allow sufficient time for your eyes to get used to the dark. You must also allow for continued dark adaptation during the observing period. During the first minute, the eye's sensitivity increases ten fold. In 20 minutes it increases 6000 fold and forty minutes of dark adaptation increases sensitivity 25,000 times!
This means that a faint object which was overlooked in an early part of your observing run may be readily seen later, so don't expect to see faint objects at their best until at least a half hour into an observing session.

Note that light adaptation is much faster that dark adaptation, so even a brief exposure to light will destroy your night vision. It is also best to consistently avoid all light for as long as possible before observing. Prolonged exposure to bright sunlight reduces your ability to dark adapt for a couple of days; wear dark glasses at the beach. In the long run, ultraviolet light ages both the eye lens and retina, reducing sensitivity. So if you wear eyeglasses outdoors, ask your optometrist for UV-filtering lenses. Night vision is also impaired by alcohol, low oxygen and low blood sugar. So don't observe while drinking, smoking or fasting. In fact, nicotine retards dark adaptation to such an extent that even a single cigarette smoked half an hour before your eyes start dark adapting will slow down this process.

This all-in-one device allows you to measure temperature, humidity, and solar radiation in a single device. Our combination offers a substantial savings over purchasing separate devices. These units can be used to monitor environmental conditions and are an essential part of your total weather station.

You may wish to install these in multiple outdoor locations to monitor conditions for your garden and landscape areas, enabling you to select the plants most suited to the available sunlight. The solar detector detects light in the visible to infrared portion of the spectrum, with peak detection at 860nm and an acceptance angle of 140 degrees.

This device comes with dual RJ45 connectors, as well as screw terminals, for easy connection to your 1-wire network. We have also added a voltage regulator the solar sensor portion of the circuit, to prevents the sensor from overloading the 1-wire network when light levels are extremely high. This device can optionally use external power of 9-24 volts DC. Either our Power Injector or our 6 Channel Hub would provide the needed power.