13.8 billion years ago, the Universe as we know it began with the onset of the hot Big Bang. As the
… [+] Universe expanded and cooled, we formed protons and neutrons, atoms, stars, galaxies, and eventually our Solar System and planet Earth. In all the Universe, there is no one just like you, but the cosmic story unites us all.
NASA / GSFC
In all the Universe, you won’t find another planet identical to Earth.
Planet Earth, as viewed by NASA’s Messenger spacecraft as it departed from our location, clearly
… [+] shows the spheroidal nature of our planet. This is an observation that cannot be made from a single vantage point on our surface. In all the cosmos, there is no other planet identical to our own.
NASA / Messenger mission
Our planet’s 4.5 billion year history has given rise to complex, intelligent, technologically advanced life.
This tree of life illustrates the evolution and development of the various organisms on Earth.
… [+] Although we all emerged from a common ancestor more than 2 billion years ago, the diverse forms of life emerged from a chaotic process that would not be exactly repeated even if we rewound and re-ran the clock trillions of times.
Yet each of us are unique, with genetic and environmental factors that no one else possesses.
Even identical twins, which have the same exact DNA sequences, will experience different conditions
… [+] and stimuli from a very young age, resulting in an entirely unique experience in life that no one else possesses. (Noam Galai/Getty Images)
And still, every being on this planet is part of the same universal cosmic story.
Our Universe, from the hot Big Bang until the present day, underwent a huge amount of growth and
… [+] evolution, and continues to do so. Although we have a large amount of evidence for dark matter, it doesn’t really make its presence known until many years have passed since the Big Bang, which means that dark matter may have been created at that time or earlier, with many scenarios remaining viable.
NASA / CXC / M.Weiss
Everyone’s atoms arose from the same pre-solar nebula, which formed the Sun and all the planets.
An illustration of the young solar system Beta Pictoris, somewhat analogous to our own Solar System
… [+] during its formation. The inner worlds, unless they’re massive enough, will not be able to hold onto their hydrogen and helium.
AVI M. MANDELL, NASA
That nebula came from a molecular cloud of gas that collapsed, forming thousands of stars.
This evocative image shows a dark cloud where new stars are forming along with a cluster of
… [+] brilliant stars that have already emerged from their dusty stellar nursery. This cloud is known as Lupus 3 and it lies about 600 light-years from Earth in the constellation of Scorpius (The Scorpion). It is likely that the Sun formed in a similar star formation region more than four billion years ago.
Its composition was from pristine material combined with the corpses of millions of other stars.
A young, star-forming region found within our own Milky Way. Note how the material around the stars
… [+] gets ionized, and over time becomes transparent to all forms of light. Star-forming regions in the Milky Way are few in number and small in nature, particularly in comparison to the more active galaxies in our Universe.
NASA, ESA, AND THE HUBBLE HERITAGE (STSCI/AURA)-ESA/HUBBLE COLLABORATION; ACKNOWLEDGMENT: R. OâCONNELL (UNIVERSITY OF VIRGINIA) AND THE WFC3 SCIENTIFIC OVERSIGHT COMMITTEE
Those prior generations of stars formed in bursts, triggered by our spiral arms and galactic mergers.
Zw II 96 in the constellation of Delphinus, the Dolphin, is an example of a galaxy merger located
… [+] some 500 million light-years away. Star formation is triggered by these classes of events, and can use up large amounts of gas within each of the progenitor galaxies, rather than a steady stream of low-level star formation found in isolated galaxies. Note the streams of stars between the interacting galaxies.
NASA, ESA, the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University)
When those earlier stars died, they ejected material, but dark matter’s gravitational pull helped retain them.
Galaxies undergoing massive bursts of star formation can outshine even much larger, typical
… [+] galaxies. M82, the Cigar Galaxy, is gravitationally interacting with its neighbor (not pictured), causing this burst of active, new star formation, which expels gas from its central region. The effects of the stellar winds are clearly visible in red, but the presence of dark matter keeps this material from being ejected.
NASA, ESA, and The Hubble Heritage Team (STScI/AURA)
Only dark matter’s influence allowed our modern cosmic web to form.
The growth of the cosmic web and the large-scale structure in the Universe, shown here with the
… [+] expansion itself scaled out, results in the Universe becoming more clustered and clumpier as time goes on. Initially small density fluctuations will grow to form a cosmic web with great voids separating them, but what appear to be the largest wall-like and supercluster-like structures may not be true, bound structures after all.
Without it, the first stellar cataclysms would have blown early proto-galaxies apart.
Two supernova remnants, G1.9+0.3 and Cassiopeia A, are shown here as imaged by a variety of NASA’s
… [+] Great Observatories. Both of these supernovae occurred subsequent to 1604, which is when the last naked eye supernova occurred in the Milky Way. Without dark matter, supernova explosions would blast early star clusters apart, preventing the formation of galaxies.
NASA/CXC/NCSU/K.Borkowski et al. (L); NASA, ESA, and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration; Acknowledgment: R. Fesen (Dartmouth College) and J. Long (ESA/Hubble) (R)
Dark matter enabled heavy elements to participate in future star-formation episodes, making rocky planets (and human beings) possible.
30 protoplanetary disks, or proplyds, as imaged by Hubble in the Orion Nebula. Forming a star with
… [+] rocky planets around them is relatively easy if you have lots of heavy elements, but impossible if you do not. Forming a rocky planet with Earth-like conditions, in subtle-but-important ways, is far more challenging.
NASA/ESA and L. Ricci (ESO)
From inflation to the Big Bang to the formation of atoms, stars, and galaxies, we all share the same cosmic story.
The earliest stages of the Universe, before the Big Bang, are what set up the initial conditions
… [+] that everything we see today has evolved from. This was Alan Guth’s big idea: cosmic inflation, which gave rise after 13.8 billion years of cosmic evolution to the Universe we inhabit today.
E. Siegel, with images derived from ESA/Planck and the DoE/NASA/ NSF interagency task force on CMB research
Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words. Talk less; smile more.