Defining questions for astronomy and astrophysics:
How were the universe and its constituent galaxies, stars, and planets formed?
How did they evolve?
What will their destiny be?
Strategy to achieve that goal:
Survey the universe and its constituents (galaxies and their evolution, stars in formation stage, interstellar and intergalactic matter, dark matter and dark energy).
Use the universe as a unique laboratory for understanding physics.
Search for life beyond Earth and, if it is found, determine its nature and distribution.
Develop a conceptual framework accounting for all observations made.
Key problems ripe for advance in this decade:
Determine large-scale properties of the universe: its age, the nature (amount and distribution) of the matter and energy that make it up, and the history of its expansion.
Study the dawn of the modern universe, when the first stars and galaxies formed.
Understand the formation and evolution of black holes of all sizes.
Study the formation of stars and their and planetary systems, and the birth and evolution of giant and terrestrial planets.
Understand how the astronomical environment affects Earth.
What is the dark matter?
What is the nature of the dark energy?
How did the universe begin?
Did Einstein have the last word on gravity?
What are the masses of the neutrinos, and how have they shaped the evolution of the universe?
How do cosmic accelerators work and what are they accelerating?
Are protons unstable?
Are there new states of matter at exceedingly high density and temperature?
Are there additional space-time dimensions?
How were the elements from iron to uranium made?
Is a new theory of matter and light needed at the highest energies?