Learn more about Skyclock company.
Read License Agreement.
Click here to view the Glossary of TermsFrequently Asked Questions
Does Skyclock work anywhere in the world?Yes. Why doesn’t Skyclock show all of the night-time hours as black?During the time known as twilight, the hours are shown as gray. The remainder of night time hours are shown as black. How does Skyclock work?Skyclock shows relative specific solar time. That is, using the current date, sunrise and sunset times, and a specific location, Skyclock calculates and displays daylight, slice-of-pie twilight, and night. Sunrise and sunset times are based on calculations, or algorithms, that result in a large set of tables. The facts have been checked for hundreds, if not thousands of years, going back to the Egyptians, who had a 365 day calendar. We know when sunset occurs for a specific place on a certain date. Our ancestors watched and marked and measured, so that today we can predict where the sun is—we know its hour angle for any place if we know the date. What we know is transient, or dynamic, because the earth’s surface is in constant motion. Four solid facts combine to inform when sunset and sunrise occur:
Twilight is then displayed as a distinct pie-shape on an analog face between blue (day) and black (night). What sunrise and sunset times are represented on the clock face?Skyclock uses nautical twilight as the basis for the gray part of the clock face. Is there any information about the moon or phases of the moon on Skyclock?No. Skyclock is based on solar events and positions. Where does all the information in Skyclock about sunrise and sunset times come from?The position of the sun relative to the earth comes from The Multiyear Interactive Computer Almanac 1800-2050 published by the U. S. Naval Observatory. Skyclock then uses the latitude, longitude and time zone for the desired location and transforms the position of the sun to a graphic display on an analog clock face. Is a GPS device necessary to use Skyclock?No. Skyclock determines latitude, longitude and time zone given the specified location. What are the differences between astronomical, civil, and nautical twilight times?Astronomical, civil, and nautical twilight times are all defined by the position of the sun measured in degrees beyond the horizon of the Earth. Please see the Glossary for more complete explanations of these terms.Why does Skyclock sometimes show (See FAQ) for some sunrise and/or twilight times?For locations north of 55 degrees north latitude or south of 55 degrees south latitude, and during certain times of the year, it will be twilight all night (in other words, it never gets completely dark). In such cases Skyclock cannot display the start and end of twilight since the twilight period lasts all night, so it simply says “(See FAQ)”. For locations north of 67 degrees north latitude or south of 67 degrees south latitude, and during certain times of the year, the sun will never go below the horizon (this is known as “midnight sun”). In such cases Skyclock cannot display sunrise or sunset, since neither occurs that day. It simply says “(See FAQ)” in such cases. I don’t see my country in the list of countries. What do I do?Some countries have been known by different names over time. Try some alternate names. I don’t see my city in the list of cities. What do I do?Skyclock has a list of many cities worldwide, but does not list every city. Pick a city near your location. I entered “full screen” mode and I don’t see how to return to normal mode.Press the Escape key. What is Sky Calendar?Sky Calendar is a feature that allows the user to look at conditions on a future date. What are noctilucent clouds?Noctilucent clouds are “night-shining clouds” (NSCs), that dwell very high in the atmosphere, or mesosphere. They are often light blue, and assume odd shapes, such as strings. They are composed of water ice. What is crepuscular?It’s an adjective relating to twilight. Also, an older person can be said to have “...crepuscular charm.” What is midnight sun?In high latitudes it is the sun, visible 24 hours. What is afterglow?Afterglow is less-than-dark sky seen after sunset, sometimes called afterlight. What is airglow?Airglow is a weak light emission in the earth’s atmosphere, also known as the faint glow of the night sky. What is a shadow?A shadow is a dark image caused by a body’s interception of light. What is a clock dial?A clock dial is a clock face upon which “hands” or indicators point to certain numbers or tick marks. What is length of sunlight?Length of sunlight is the amount of time, measured in hours and minutes, that the sun is above the horizon. What is a golden hour?a. In medicine, the sixty minutes after an accident. b. In photography, when the sun’s shadows are orange, or “golden.” |