# astrophysics

posted by .

1) Every second the Sun outputs 3.90* 10^26 Joules of energy. Power is energy output per unit

time and is given in units of Watts (W) where 1 W = 1 Joule per second. The Sun's power

output is therefore 3.90*10^26 Watts. This is called the solar luminosity. As this energy travels

outward from the Sun it is spread (fairly evenly) over a spherical surface that increases in area

with distance from the Sun (recall the area of a sphere is proportional to its radius squared).

The energy received each second by an area of 1 m2 is called the energy flux.

a) Calculate the energy °ux from the Sun at a distance of 9:54 AU (that is, Saturn's mean

distance) from the Sun. How does this compare with the solar flux received at the Earth's

mean distance from the Sun?

b) Suppose we place a perfectly black sphere with radius 2600 km at a distance of 9:54 AU from

the Sun. How much direct solar energy does the sphere absorb in one second?

c) If the sphere in part (b) is in thermal equilibrium, what is its temperature?

d) Titan re°ects approximately 20% of the light that strikes its surface, and absorbs the rest.
Titan's radius is roughly 2600 km. How much energy from sunlight does Titan absorb each
second? What is the temperature of Titan if it has no internal heat sources of significance?

• astrophysics -

These are exercises in using the inverse square law of luminosity and the blackbody law of thermal radiation. You will be helped if you first make an effort and show your work.

## Respond to this Question

 First Name School Subject Your Answer

## Similar Questions

1. ### Physics

Hi can someone advise whether my methodology is right on this with a potential energy of 589 kJ per tonne, 100 tonnes of water per second are delivered to a turbine. Assuming all the potential energy of this water is used to drive …
2. ### Physics - solar power in space

Hi, this requires some basic knowledge of astrophysics. I missed last lecture that covered this, so though I'd prefer thorough solutions to these problems, I'd appreciate it even if you could tell me which formulas to use to solve …
3. ### astrophysics

1) Every second the Sun outputs 3.90* 10^26 Joules of energy. Power is energy output per unit time and is given in units of Watts (W) where 1 W = 1 Joule per second. The Sun's power output is therefore 3.90*10^26 Watts. This is called …
4. ### Physics

Approximately 4 x 10^9 kg of matter is converted into enery in the sun per second. Express the power output of the sun in watts.
5. ### Integrated Science

The sun converts matter to radiant energy at a rate of 1.4 x 10 to the 17th power kg per year, how much matter is converted into energy every second?
6. ### science

The total power output of the Sun is about 3.8 × 1026 W, and the power-producing core has a radius of about 1.4 × 105 km (about 20% of the full radius of the Sun). Using these figures and your knowledge of the energy release in the …
7. ### Physics

Approximately 4x10^9 kg of matter is converted into energy in the sun per second. Express the power output of the sun in watts.
8. ### physics

The power output in the sun is about 4.00 x 10^26W. (a). Calculate the power per unit area (intensity), in kilowatts per square meter, reaching Earth's upper atmosphere from the sun. The radius of the Earth's orbit is 1.5 x 10^11m.
9. ### Chemistry

You leave 255 grams of water outside at 21.0 C in the sun. After 30.0 minutes the temperature is 35.0 C. A) how many calories of energy was used by the sun to heat the water up?
10. ### Physics

The temperature of the Sun’s surface (the so-called photosphere) is about 5500 C. Assume that the Sun’s surface is pretty close to a perfect black-body emitter. (a) At what wavelength does the peak intensity of Sun’s radiation …

More Similar Questions