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The Wonder of It AllThe universe has been around for roughly 13.7 billion years, but it still holds many mysteries that continue to perplex astronomers to this day. Ranging from dark energy to cosmic rays to the uniqueness of our own solar system, there is no shortage of cosmic oddities.
The journal Science summarized some of the most bewildering questions being asked by leading astronomers today. In no particular order, here are eight of the most enduring mysteries in astronomy:
FIRST STOP: Dark Energy
What is Dark Energy?Slide 2 of 18
What is Dark Energy?Dark energy is thought to be the enigmatic force that is pulling the cosmos apart at ever-increasing speeds, and is used by astronomers to explain the universe's accelerated expansion.
This elusive force has yet to be directly detected, but dark energy is thought to make up roughly 73 percent of the universe.
NEXT STOP: Dark MatterSlide 3 of 18
How Hot is Dark Matter?Slide 4 of 18
How Hot is Dark Matter?Dark matter is an invisible mass that is thought to make up about 23 percent of the universe. Dark matter has mass but cannot be seen, so scientists infer its presence based on the gravitational pull it exerts on regular matter.
Researchers remain curious about the properties of dark matter, such as whether it is icy cold as many theories predict, or if it is warmer.
NEXT UP: Missing BaryonsSlide 5 of 18
Where are the Missing Baryons?Slide 6 of 18
Where are the Missing Baryons?Dark energy and dark matter combine to occupy approximately 95 percent of the universe, with regular matter making up the remaining 5 percent. But, researchers have been puzzled to find that more than half of this regular matter is missing.
This missing matter is called baryonic matter, and it is composed of particles such as protons and electrons that make up majority of the mass of the universe's visible matter.
Some astrophysicists suspect that missing baryonic matter may be found between galaxies, in material known as warm-hot intergalactic medium, but the universe's missing baryons remain a hotly debated topic.
NEXT UP: Supernova ExplosionsSlide 7 of 18
How do Stars Explode?Slide 8 of 18