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Over watering is as bad as under watering, so always check the soil before turning on a tap or hitting the rain barrels. Foliar feeds like compost tea can be added to give plants extra nutrition and a dose of healthy microbes while watering. Young plants are easier to damage than older plants, so they may need protection or hardening off when they are planted outside.
Theoretical models of the Sun's development suggest that 3.8 to 2.5 billion years ago, during the Archean eon, the Sun was only about 75% as bright as it is today. Such a weak star would not have been able to sustain liquid water on Earth's surface, and thus life should not have been able to develop. However, the geological record demonstrates that Earth has remained at a fairly constant temperature throughout its history and that the young Earth was somewhat warmer than it is today. Long-term secular change in sunspot number is thought, by some scientists, to be correlated with long-term change in solar irradiance, which, in turn, might influence Earth's long-term climate. The solar cycle influences space weather conditions, including those surrounding Earth.
Seasonal affective disorder (SAD)
A higher number means greater risk of exposure to UV rays and a higher chance of sunburn and skin damage that could ultimately lead to skin cancer. The UV Index is part of many weather forecasts throughout the country. Further information about the UV Index, as well as your local UV Index forecast, can be found on the EPA’s website at /sunsafety/uv-index-1. The solar constant is a measure of flux density, is the amount of incoming solar electromagnetic radiation per unit area that would be incident on a plane perpendicular to the rays, at a distance of one astronomical unit . The "solar constant" includes all types of solar radiation, not just the visible light. Its average value was thought to be approximately 1366 W/m2, varying slightly with solar activity, but recent recalibrations of the relevant satellite observations indicate a value closer to 1361 W/m2 is more realistic.
One of the first people to offer a scientific or philosophical explanation for the Sun was the Greek philosopher Anaxagoras. He reasoned that it was not the chariot of Helios, but instead a giant flaming ball of metal even larger than the land of the Peloponnesus and that the Moon reflected the light of the Sun. For teaching this heresy, he was imprisoned by the authorities and sentenced to death, though he was later released through the intervention of Pericles. In the first century AD, Ptolemy estimated the distance as 1,210 times the radius of Earth, approximately 7.71 million kilometers (0.0515 AU).
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The heavy elements could most plausibly have been produced by endothermic nuclear reactions during a supernova, or by transmutation through neutron absorption within a massive second-generation star. The term sol with a lower-case s is used by planetary astronomers for the duration of a solar day on another planet such as Mars. Cognitive behavioral therapy is a type of talk therapy aimed at helping people learn how to cope with difficult situations; CBT also has been adapted for people with SAD (CBT-SAD). It is typically conducted in two weekly group sessions for 6 weeks and focuses on replacing negative thoughts related to the winter season (e.g., about the darkness of winter) with more positive thoughts. CBT-SAD also uses a process called behavioral activation, which helps individuals identify and schedule pleasant, engaging indoor or outdoor activities to combat the loss of interest they typically experience in the winter. Both serotonin and melatonin help maintain the body’s daily rhythm that is tied to the seasonal night-day cycle.
In the early years of the modern scientific era, the source of the Sun's energy was a significant puzzle. Lord Kelvin suggested that the Sun is a gradually cooling liquid body that is radiating an internal store of heat. In 1890 Joseph Lockyer, who discovered helium in the solar spectrum, proposed a meteoritic hypothesis for the formation and evolution of the Sun. The Solar System is located in the Milky Way, a barred spiral galaxy with a diameter of about 100,000 light-years containing more than 100 billion stars. The Sun resides in one of the Milky Way's outer spiral arms, known as the Orion–Cygnus Arm or Local Spur.
The next frontier for rewilding? Pub gardens
The Sunlight Foundation is a national, nonpartisan, nonprofit organization that uses the tools of civic tech, open data, policy analysis, and journalism to make our government and politics more accountable and transparent to all. Our vision is for modern technology to enable more complete, equitable and effective democratic participation. Our overarching goal is to achieve changes in the law to require real-time, online transparency for government information. A drop in serotonin, a brain chemical that affects mood, might play a role in SAD. Reduced sunlight can cause a drop in serotonin that may trigger depression.
Sunshine is often blocked from entering buildings through the use of walls, window blinds, awnings, shutters, curtains, or nearby shade trees. Sunshine exposure is needed biologically for the production of Vitamin D in the skin, a vital compound needed to make strong bone and muscle in the body. The existence of nearly all life on Earth is fueled by light from the Sun.
The high temperature of the corona shows that it is heated by something other than direct heat conduction from the photosphere. In 1666, Isaac Newton observed the Sun's light using a prism, and showed that it is made up of light of many colors. In 1800, William Herschel discovered infrared radiation beyond the red part of the solar spectrum. The 19th century saw advancement in spectroscopic studies of the Sun; Joseph von Fraunhofer recorded more than 600 absorption lines in the spectrum, the strongest of which are still often referred to as Fraunhofer lines. The 20th century brought about several specialized systems for observing the sun, especially at different narrowband wavelengths, such as those using Calcium H (396.9 nm), K (393.37 nm) and Hydrogen-alpha (656.46 nm) filtering. The closest solitary Sun-like star to the Solar System is Tau Ceti at 11.9 light-years.
The Sun today is roughly halfway through the most stable part of its life. It has not changed dramatically for over four billion years and will remain fairly stable for more than five billion more. However, after hydrogen fusion in its core has stopped, the Sun will undergo dramatic changes, both internally and externally.
Most autotrophs, such as plants, use the energy of sunlight, combined with carbon dioxide and water, to produce simple sugars—a process known as photosynthesis. These sugars are then used as building-blocks and in other synthetic pathways that allow the organism to grow. Thus, it would give perceptions and "feel" very much like Earth daylight.
You may be able to head off serious changes in mood, appetite and energy levels, as you can predict the time of the year in which these symptoms may start. Treatment can help prevent complications, especially if SAD is diagnosed and treated before symptoms get bad. But if you feel down for days at a time and you can't get motivated to do activities you normally enjoy, see your health care provider. This is especially important if your sleep patterns and appetite have changed, you turn to alcohol for comfort or relaxation, or you feel hopeless or think about suicide.
Seasonal affective disorder is a type of depression with a recurring seasonal pattern, with symptoms most often starting in the late fall and early winter and going away in the spring and summer. The risk of SAD is higher in people who live far from the equator and those with a personal or family history of depression. Women are more likely than men to develop SAD, and younger people have a higher risk than older ones. People who are using PUVA or other forms of light therapy should limit or avoid exposure to natural sunlight unless directed by a health care provider. The preponderance of hydrogen in the Sun was confirmed in 1925 by Cecilia Payne using the ionization theory developed by Meghnad Saha. The theoretical concept of fusion was developed in the 1930s by the astrophysicists Subrahmanyan Chandrasekhar and Hans Bethe.
At GGGSC, we apply expertise in geology, geophysics, and geochemistry to interdisciplinary efforts in support of the USGS mission to address the Nation’s important earth science issues, with an emphasis on mineral resources. This publication is in the public domain and may be reproduced or copied without permission from NIMH. To learn more about using NIMH publications, refer to our reprint guidelines.
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