# Is the sun getting hotter? **URL:** \ **Category:** Factual Questions\ **Created:** [August 14, 2006, 5:05pm UTC](https://boards.straightdope.com/t/is-the-sun-getting-hotter/368693 "2006-08-14T17:05:11Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![XT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/xt/32/456_2.png) [@XT](https://boards.straightdope.com/u/XT)\ **Post date:** [August 14, 2006, 5:05pm UTC](https://boards.straightdope.com/t/is-the-sun-getting-hotter/368693/1 "2006-08-14T17:05:11Z")
I was watching a show on National Geographic Channel this weekend and they were talking about the Sun (the show was called Naked Science). One of the things they mentioned was that the sun was getting hotter…its (according to the show) 30% ‘brighter’ than it was when it first formed, and rises about 10% every billion years. Does ‘brighter’ equal ‘hotter’? If so, how does this factor into the whole Global Warming issue…or does it not factor in at all? If it is getting hotter how long does the earth have until its basically uninhabitable? Would 10% more heat in a billion years do it for the earth pretty much? -XT ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [August 14, 2006, 7:53pm UTC](https://boards.straightdope.com/t/is-the-sun-getting-hotter/368693/2 "2006-08-14T19:53:05Z")
It is getting brighter, and that does imply hotter (though the relationship is not linear). But timescales in the billions of years are completely irrelevant to global warming: Most global warming studies look at timescales from about a hundred years to perhaps tens of thousands. On those scales, changes in the Sun itself are only just barely detectable by the most sensitive measurements. ---
**Author:** ![Steve\_MB](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/steve_mb/32/5339_2.png) [@Steve\_MB](https://boards.straightdope.com/u/Steve_MB)\ **Post date:** [August 14, 2006, 8:50pm UTC](https://boards.straightdope.com/t/is-the-sun-getting-hotter/368693/3 "2006-08-14T20:50:35Z")
> [@Chronos](#): > > It is getting brighter, and that does imply hotter (though the relationship is not linear). But timescales in the billions of years are completely irrelevant to global warming: Most global warming studies look at timescales from about a hundred years to perhaps tens of thousands. On those scales, changes in the Sun itself are only just barely detectable by the most sensitive measurements. The steady increase in the Sun’s brightness during its main-sequence lifetime (as its helium core gets bigger) is too slow to be relevant to global warming. However, other short-term variations in solar output (e.g. the Maunder Minimum occur on a more relevant timescale (e.g. the Maunder Minimum appears to correspond to the “Little Ice Age”). ---
**Author:** ![lieu](https://avatars.discourse-cdn.com/v4/letter/l/c2a13f/32.png) [@lieu](https://boards.straightdope.com/u/lieu)\ **Post date:** [August 14, 2006, 8:52pm UTC](https://boards.straightdope.com/t/is-the-sun-getting-hotter/368693/4 "2006-08-14T20:52:29Z")
Good show! I caught parts of it too. Like **Chronos** said though, it’s negligable in a global warming sense, far outweighed by other current processes and an extrodinary long time before appreciably realized. What I found amusing was when they’d talk of the effects this rise in temps would have on man in a billion or two years. I’d rate the notion we’ll be here as applaudably optimistic. ---
**Author:** ![mks57](https://avatars.discourse-cdn.com/v4/letter/m/b9bd4f/32.png) [@mks57](https://boards.straightdope.com/u/mks57)\ **Post date:** [August 14, 2006, 10:00pm UTC](https://boards.straightdope.com/t/is-the-sun-getting-hotter/368693/5 "2006-08-14T22:00:33Z")
I was told by my astronomy professor that I didn’t have to worry about the Sun becoming a red giant. The steady increase in solar output would push the Earth into thermal runaway, like Venus, well before that happened. We’re doomed. ---
**Author:** ![Ogre](https://avatars.discourse-cdn.com/v4/letter/o/ecb155/32.png) [@Ogre](https://boards.straightdope.com/u/Ogre)\ **Post date:** [August 14, 2006, 10:05pm UTC](https://boards.straightdope.com/t/is-the-sun-getting-hotter/368693/6 "2006-08-14T22:05:26Z")
> [@mks57](#): > > I was told by my astronomy professor that I didn’t have to worry about the Sun becoming a red giant. The steady increase in solar output would push the Earth into thermal runaway, like Venus, well before that happened. We’re doomed. …asuming we don’t move out of the neighborhood in, say, the next 5 billion years or so. 🙂 ---
**Author:** ![XT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/xt/32/456_2.png) [@XT](https://boards.straightdope.com/u/XT)\ **Post date:** [August 14, 2006, 10:15pm UTC](https://boards.straightdope.com/t/is-the-sun-getting-hotter/368693/7 "2006-08-14T22:15:08Z")
> [@Ogre](#): > > …asuming we don’t move out of the neighborhood in, say, the next 5 billion years or so. Well, according to the show I mentioned in the OP its 10:45am (the sun being born at 6am and dieing at 6pm)…and the planet will be uninhabitable by 11:30am. So…we actually have less than an hour (which I think translates into less than one billion years) before the average surface temperature is something like 170 degrees F. :eek: If the show is right of course. Thats why I started the OP. 🙂 -XT ---
**Author:** ![Der\_Trihs](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/der_trihs/32/233_2.png) [@Der\_Trihs](https://boards.straightdope.com/u/Der_Trihs)\ **Post date:** [August 14, 2006, 10:24pm UTC](https://boards.straightdope.com/t/is-the-sun-getting-hotter/368693/8 "2006-08-14T22:24:11Z")
> [@mks57](#): > > I was told by my astronomy professor that I didn’t have to worry about the Sun becoming a red giant. The steady increase in solar output would push the Earth into thermal runaway, like Venus, well before that happened. We’re doomed. Well, we could set up gigantic sunshades in space, or even move the planet outward in theory. ---
**Author:** ![Ogre](https://avatars.discourse-cdn.com/v4/letter/o/ecb155/32.png) [@Ogre](https://boards.straightdope.com/u/Ogre)\ **Post date:** [August 14, 2006, 10:32pm UTC](https://boards.straightdope.com/t/is-the-sun-getting-hotter/368693/9 "2006-08-14T22:32:41Z")
> [@xtisme](#): > > Well, according to the show I mentioned in the OP its 10:45am (the sun being born at 6am and dieing at 6pm)…and the planet will be uninhabitable by 11:30am. So…we actually have less than an hour (which I think translates into less than one billion years) before the average surface temperature is something like 170 degrees F. :eek: If the show is right of course. > > Thats why I started the OP. 🙂 > > -XT A billion years is stil puh-lenty of time to pack up and move to greener (or purpler, or tealer, or whatever-er) pastures. 🙂 ---
**Author:** ![Gorsnak](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gorsnak/32/7587_2.png) [@Gorsnak](https://boards.straightdope.com/u/Gorsnak)\ **Post date:** [August 14, 2006, 10:32pm UTC](https://boards.straightdope.com/t/is-the-sun-getting-hotter/368693/10 "2006-08-14T22:32:59Z")
> [@Der Trihs](#): > > Well, we could set up gigantic sunshades in space, or even move the planet outward in theory. Moving the planet would require ridiculous amounts of energy. Giant sunshades are clearly the way to go. Where’s Mr. Burns? ---
**Author:** ![Der\_Trihs](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/der_trihs/32/233_2.png) [@Der\_Trihs](https://boards.straightdope.com/u/Der_Trihs)\ **Post date:** [August 14, 2006, 10:43pm UTC](https://boards.straightdope.com/t/is-the-sun-getting-hotter/368693/11 "2006-08-14T22:43:05Z")
> [@Gorsnak](#): > > Moving the planet would require ridiculous amounts of energy. Or a _lot_ of time. I recall one claim from a scientist a while back that you could do it just by carefully moving an asteroid into repeated, constant near misses of the Earth. Do it right for enough millions of year and the repeated tiny tugs will move the planet. OTOH sunshades are rather less likely to smash the biosphere if you make one tiny mistake over those millions of years. ---
**Author:** ![XT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/xt/32/456_2.png) [@XT](https://boards.straightdope.com/u/XT)\ **Post date:** [August 14, 2006, 11:10pm UTC](https://boards.straightdope.com/t/is-the-sun-getting-hotter/368693/12 "2006-08-14T23:10:21Z")
Anyone know what a hotter sun will do to the outer planets in the solar system? What will, say, Mars be like when the earth is toasting at 170 degrees F on average? How about the gas giants? -XT ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [August 14, 2006, 11:14pm UTC](https://boards.straightdope.com/t/is-the-sun-getting-hotter/368693/13 "2006-08-14T23:14:29Z")
> [@Der Trihs](#): > > Or a _lot_ of time. I recall one claim from a scientist a while back that you could do it just by carefully moving an asteroid into repeated, constant near misses of the Earth. Do it right for enough millions of year and the repeated tiny tugs will move the planet. OTOH sunshades are rather less likely to smash the biosphere if you make one tiny mistake over those millions of years. You’d have to get the asteroid to steal energy from some other planet (say, Mars) at the other end of each orbit, by dragging that planet down toward the sun a bit, otherwise it would need constant boosting to keep it going, the energy for which would be equivalent to the total amount needed to move the Earth. ---
**Author:** ![Der\_Trihs](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/der_trihs/32/233_2.png) [@Der\_Trihs](https://boards.straightdope.com/u/Der_Trihs)\ **Post date:** [August 15, 2006, 12:57am UTC](https://boards.straightdope.com/t/is-the-sun-getting-hotter/368693/14 "2006-08-15T00:57:31Z")
> [@Mangetout](#): > > You’d have to get the asteroid to steal energy from some other planet (say, Mars) at the other end of each orbit, by dragging that planet down toward the sun a bit, otherwise it would need constant boosting to keep it going, the energy for which would be equivalent to the total amount needed to move the Earth. Yes, or a solar sail. Yes it still would take energy, but the energy involved is there for the taking anyway. Or, you could use a sail powered by Mercury-mounted solar powered lasers if you want more push. _Anything_ you do is going to take energy, including the sunshade idea ( it has to be built, set up and maintained, after all ). Therefore the practical question is one of energy _density_; in other words, how much energy do you need at any one time ? The asteroid idea involves a reasonable amount of energy. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [August 15, 2006, 1:24am UTC](https://boards.straightdope.com/t/is-the-sun-getting-hotter/368693/15 "2006-08-15T01:24:04Z")
> [@Der Trihs](#): > > I recall one claim from a scientist a while back that you could do it just by carefully moving an asteroid into repeated, constant near misses of the Earth… [Planet Earth on the move](http://news.bbc.co.uk/2/hi/science/nature/1154784.stm) > [@](#): > > All that is required is for a large asteroid, about 100 km (62 miles) across, to fly past the Earth transferring some of its orbital energy to our planet. The asteroid would then move out to encounter Jupiter where it would acquire more energy that it could impart to the Earth on a subsequent encounter.