# What would be the effect of a 90% weaker Sun?

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#### thedoc

• Sr. Member
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##### What would be the effect of a 90% weaker Sun?
« on: 14/06/2012 19:30:01 »
RON1  asked the Naked Scientists:

If we reduce (providing this is possible) the power of the sun by 90% (like a 100 watt lightbulb to 10 watt bulb) what will happen to the sun after billions of years?

Best regards,

Roni

What do you think?
« Last Edit: 14/06/2012 19:30:01 by _system »

#### Pmb

• Neilep Level Member
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##### Re: What would be the effect of a 90% weaker Sun?
« Reply #1 on: 14/06/2012 19:56:35 »
If you decreased the size of the sun then you'd have to take out a huge amount of mass and then there'd be a lack of force to hold the sun intact resulting in a supernova.

#### CliffordK

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##### Re: What would be the effect of a 90% weaker Sun?
« Reply #2 on: 15/06/2012 01:48:39 »
There are many smaller stars than our own.

The smaller the star, the cooler it burns, and thus the longer it will last.

Here is a calculation for the lifespan of main sequence stars:

Lifespan = $$\frac{10}{M^{2.5}}$$ where M is the mass of the star in solar masses, and the lifespan is in billions of years.

1 solar mass would give about 10 billion years.
0.1 solar masses would give about 3,162 billion years, or about 300x the lifespan of our sun.