when does the sun expires?
84417
The Sun is currently about 5 billion years old, "burning" hydrogen by fusing hydrogen into helium. The fusion only works in the core, where the temperature and pressure is high enough.\n\nWhen the hydrogen is used up the Sun will begin to contract. Eventually the core will become hot enough that helium will start to fuse. During this time the outer layers of the Sun will expand. This is the Red Giant phase.\n\nFairly soon after this (astronomically speaking) the Sun will run out of helium. Again the sun will contract, but this time not enough to heat the core for helium to burn (helium burning happens in massive stars). \n\nAt this stage the Sun will continually contract, glowing fainter and fainter with energy derived from the collapse and not fusion, until the remnant Sun is compressed so much that it is about the size of the Moon. At the begining of this collapse more gas is lost from the outer layers of the Sun, forming what is known as a "Planetary Nebulae," a shell of gas that has nothing to do with planets.\n\nThe white dwarf stage is very, very long. The Sun will slowly fade until it is barely radiating and is a cold, bare "black dwarf."  The Sun will NOT turn into a black hole.\n\n\nSo the answer is:\n--The Sun is about 5 billion years old.\n--The Red Giant phase will occur in about 5 billion years\n--Sun as a White dwarf - starting about 5 billion from now, and ending about 10 or 15 billion years from now.\n--Sun as a cold, black dwarf - as long as the Sun doesn't crash into anything, this stage may last for hundreds of billions of years
869394
Strongest UV radiation would have to be on 21. December each year, but it also depends on the weather. You often get clearer skies in January and February than in December and the months before, which means the risk of getting sunburned is realistically going to be higher then.
152502
I would say it depends on what you mean by official. But The first day of a new season is often taken as a solistice, or an equinox. In the northern Hemisphere, that would make the last day of summer roughly September 21th, since September 22st is the fall or autumnal equinox. \n\nThe equinox is that date at which the day and the night are roughly of equal length, and the sun crosses the celestial equator. \n\nThe last day of summer in the southern hemisphere is of course the day before the vernal equinox, or March 19 or so.
868570
The answer depends on many things....\n1st if you are looking for a scientific answer the Solstice is June 21st... this is the official day of summer.  So part of June is spring, the other part is summer.  However if you are in the southern hemisphere it is late fall... early winter...\n\nYou have already got that response... but if you are a teacher... June is part of our summer vacation... or for some the beginning of "summer school" so in my world... June is one of the great things about being a teacher.... SUMMER!!!
656942
You have up to three months to fill it. Once you fill it, it expires one year from that date
49642
The spring season starts on March 20th or 21st depending on when the equinox is. The equinox is when the length of day and night is equal and happens twice a year in spring and autumm. Spring ends in May. This is only offically the weather changes and means that our winters are getting shorter and flowers are growing much earlier then ever before.
375923
The sun is a powerful thermonuclear device.  Very little will withstand exposure to sunlight forever.\n\nTypical modern plastic based solar cells will last for 15 to 20 years.  "Glass technology" can be extended to 25 to 30 years.  Premium quality last as long as 50 years and counting.
886955
much longer than we as a species will i think..., i think professor hawkins has classed our sun as 'middle aged' with very little sun spots (black marks) on the surface, this tells us our sun is still in a healthy condition.
100157
March 29th, 2006\n\nhttp://sunearth.gsfc.nasa.gov/eclipse/SEmono/TSE2006/TSE2006.html
737950
The sun is very gradually getting hotter. In about 5.6 billion years, most of the oceans will have boiled and most life on Earth will be gone.\n\nIn about 12.233 billion years, the sun will start to run out of fuel and become a red giant star. It will expand until the outer surface is somewhere between the present location of Earth and Mars. All life on Earth will end.\n\nThis will be because there is no more hydrogen left to make into helium in the core of the sun. When this happens, the sun will start to collapse (not enough force from core pushing out) until it starts fusing helium! This will result in a very dense and unimaginably hot core that produces so much energy that it pushes the outer layers of the sun out to where Earth is now.\n\nIn 12.365 billion years it will run out of helium too and blow its outer layers off entirely when it starts fusing heavier elements. The end result will be a white dwarf (large ball of slowly cooling fusion waste) and a very pretty, very large bubble of glowing gas that will look something like this:\n\nhttp://www.edwinhubble.com/hubble_gallery/planetary_nebula_IC_418.htm\n\nFor the complete past, present and future of our sun, click here:\nhttp://www-astronomy.mps.ohio-state.edu/~pogge/Lectures/vistas97.html
545487
The sun has lived for a long time actually the sun isn't alive but anyway stars usually live for a bout ten billion years.  they know this by looking at the history of other stars and how much they have gone out in the short amount of time  it was being studied. The sun is burning its hydrogen gas so its not a really accurate guess but its pretty close. but you wont have to worry about the sun burning out because you will already be dead for a long time.
916358
Not sure about annual total, but today the sun rose there at 6:57 AM and set at 4:50 PM... An annual total would average out to 12 hours of each, I would imagine
15450
Summer on Uranus lasts 21 years using the definition of 4 equal seasons. However, the period between vernal (spring) equinox and autumnal equinox is actually 42 years. This year is the vernal equinox.\nI quote:\n"The extreme tilt of the axis of Uranus has important implications for the weather on that planet. Consider how the seasons vary during the course of one uranian year:\n\n    * Winter solstice (which last occurred in 1985 AD):\n      The north pole is pointed almost directly away from the Sun.\n      The northern hemisphere experiences perpetual darkness.\n      The southern hemisphere experiences perpetual sunlight.\n    * Spring equinox (2006 AD):\n      The rotation axis is perpendicular to the Uranus-Sun direction.\n      From any point on Uranus, the Sun rises in the east\n      and sets in the west 8 1/2 hours later.\n    * Summer solstice (2027 AD): The north pole is pointed almost directly toward the Sun.\n      The north experiences perpetual sunlight.\n      The south experiences perpetual darkness."\n\nSource: http://users.zoominternet.net/~matto/M.C.A.S/notes_uranus__neptune.htm
1096428
It's actual called the summer solstice.  The longest day and the shortest night.  The equinoxs (spring and autumn) are named because the day and nights are equal in length of time.  The Summer Solstice is June 21.
13575
From Astronomy Magazine December 1997 \n\nOn December 21, the sun reaches the farest point south in its travels around \nthe celestrial sphere. On December 21, those of us who live in the Northern \nHemisphere will experience the shortest day of the year. You might assume \nthat the 21st also features the latest sunrise and the earliest sunset of the \nyear, but in fact, this isn't true. To understand what's happening, we have to \nexamine a lovely curve known as the analemma. We start with the fact that \nour method of reckoning time is based on the sun's daily trip across the sky. \nSpecifically, we've regarded mid-way, or "noon" as that time when the sun is \nhighest in the sky, half-way between sunrise and sunset. \nYou can generate the analemma by plotting the position of the sun in your \nsky at the same time each day, as astrophotographer Fank Zullo did several \nyears ago. Between September 9, 1990, and August 23, 1991, he made 37 \nexposures of the sun on a single film frame. Each photo was taken at exactly \n8:00 a.m. MST. He then used a simple double exposure technique, "burning in" \nthe suns into the sky above the sundial. The analemma graphically shows why \nthe latest sunrise and earliest sunset don't occur on the day of the solstice.
115975
"If you don't see a date, the rule of thumb is that the active ingredients in sunscreen (like zinc, titanium dioxide and Parsol 1789) should remain stable and effective for about three years, according to David Leffell, M.D., professor of dermatology at Yale School of Medicine. But if it smells funny, feels lumpy or has a bizarro color, dump it. To keep your sunscreen as close to new as possible, store it in a dry spot at room temperature with the lid tightly fastened."
480364
Yup. The latest will be 5 billion years from now, give or take a few hundred thousand. By then the sun will either:\n\n1) engulf our planet (very unlikely, but will come close enough to vaporize our planet)\n2) Die and not engulf or vaporize our planet and within days our atmosphere will freeze and fall to the earth in the form of ice.