<p>When Earth formed <span class="math-container">$\approx 4.5 \times 10^9$</span> years ago, Earth's surface rocks emitted more radiation because they had more unstable isotopes. All short half-life isotopes decayed long ago, and the amount of long half-life isotopes has decreased. How much radiation did rocks emit <span class="math-container">$\approx 4.5 \times 10^9$</span> years ago?</p>

CC BY-SA 4.0
2020-06-12T02:24:53.027Z
By "how much radiation" do you mean power eg., Watts?
Keith McClary
CC BY-SA 4.0
2020-06-12T08:42:54.707Z
Sievert or grey
Châu
CC BY-SA 4.0
2020-06-12T20:11:07.627Z
I think it is hard to answer. For example, imagine if there is any isotope X, which decays quickly into X', which is a major component of the crust. How can you say, how much of it was there 4.5bln year ago? I think there is no way for that. However, I believe realistic estimations should exist, using partially stellar models and astronomical results. **I vote "leave open".**
peterh
<rocks><radioactivity>
When Earth formed 4.5 × 10⁹ years ago, how much radiation did surface rocks emit?
Châu
# When Earth formed 4.5 × 10⁹ years ago, how much radiation did surface rocks emit?

(Asked by: username_0 on 2020-06-11)

When Earth formed $\approx 4.5 \times 10^9$ years ago, Earth's surface rocks emitted more radiation because they had more unstable isotopes. All short half-life isotopes decayed long ago, and the amount of long half-life isotopes has decreased. How much radiation did rocks emit $\approx 4.5 \times 10^9$ years ago?

**Tags:** rocks, radioactivity

> **Comments:**
> **username_1**: By "how much radiation" do you mean power eg., Watts?  
> **username_0**: Sievert or grey  
> **username_2**: I think it is hard to answer. For example, imagine if there is any isotope X, which decays quickly into X', which is a major component of the crust. How can you say, how much of it was there 4.5bln year ago? I think there is no way for that. However, I believe realistic estimations should exist, using partially stellar models and astronomical results. **I vote "leave open".**  

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## 0 answers

