"Unveiling the Enigma: Journey into the Mysteries of Dark Energy"

Dark energy is a mysterious form of energy that is thought to make up about 68% of the universe. It's believed to be responsible for the observed accelerated expansion of the universe. Despite its significant impact on the cosmos, its true nature remains poorly understood, and it has not been directly observed. 

In astronomy, 

Dark energy is a theoretical form of energy that is believed to permeate all of space and is responsible for the observed accelerated expansion of the universe. It is invoked to explain why galaxies are moving away from each other at an increasing rate. The exact nature of dark energy is still a subject of ongoing research and remains one of the fundamental mysteries in cosmology.

Individual Facts About Dark Energy. 

1. Discovery:

The existence of dark energy was inferred from observations of distant supernovae in the late 1990s, which revealed the accelerated expansion of the universe.

2. Cosmic Dominance:

Dark energy is thought to constitute approximately 68% of the total mass-energy content of the universe, with dark matter making up about 27%, and normal matter (atoms) comprising just 5%.

3. Constant Density:

Unlike matter, which dilutes as the universe expands, dark energy is believed to have a constant energy density. This property leads to an acceleration in the expansion of the universe.

4. Cosmological Constant:

One possible explanation for dark energy is the cosmological constant, a term in Einstein's equations of general relativity. It represents a constant energy density filling space homogeneously.

5. Repulsive Force:

Dark energy is associated with a negative pressure that counteracts the attractive force of gravity, leading to the observed acceleration of the universe's expansion.

6. Uncertain Nature:

Despite its significant role in the universe, the nature of dark energy remains elusive. Various hypotheses, including quintessence and modifications to general relativity, are being explored to understand its properties.

7. Dark Energy Survey (DES):

Initiatives like the Dark Energy Survey aim to map the distribution of dark energy by observing large regions of the sky and studying the shapes and distribution of galaxies to understand the cosmic acceleration.

Remember that our understanding of dark energy is an active area of research, and new discoveries may refine or reshape our current knowledge.