Imagine that these 100 pennies
represent the total energy input from the sun to Earth.
That energy fluctuates over time.
For a long time, scientists have known
that the sun’s energy changes in a fairly regular “solar cycle”.
The period from minimum to maximum
and back to minimum is about eleven years,
but even with those cycles, there’s very limited variation in total energy output.
These are solar energy measurements collected by a variety of missions over the years.
The question, however, is precisely—
—precisely—
—how much does the sun’s energy output change?
Experts think the number is pretty small:
perhaps just one tenth of one percent…
…a tenth of a penny.
But one tenth of one percent from the sun can have a profound influence on Earth.
In terms of climate change research, scientists need to understand
the balance between energy coming in from the Sun
and energy radiating out from Earth, as modulated by Earth’s surface and atmosphere.
That’s why NASA is launching TSIS,
the Total and Spectral Solar Irradiance Sensor.
An accurate solar energy measurement
enables other influences on Earth’s energy balance
to be isolated and more accurately quantified.
That will pay big dividends
in terms of understanding human and natural influences on Earth’s climate.