Dawn of an Era

"It's a been a long road
Getting from there to here
It's been a long time

But my time is finally here!"

—"Faith of the Heart" -- Theme song to Star Trek: Enterprise

Dawn Of An Era is when the story has a moment that will change the story world in a good way.

For instance, someone, at great personal risk, not only successfully tests a practical and reliable way to travel to different solar systems as easily as sailing across the Atlantic, but aliens detect that trip and decide to pop by to say, "Welcome to the neighborhood!"

Suddenly, all realize that their lives, their world and their very view of the universe has changed forever with marvels, technology, magic, and astounding possibilities and challenges lying before them to persuade even the most despairing soul to have faith of the heart for a glorious future.

Thanks to the heroes, a brave new world has begun where the age of wonders is just beginning.

(Err, not the bad one, we promise!)

For the opposite, see End of an Age. For a related trope, see The Magic Goes Away.

Examples of Dawn of an Era include:

Anime and Manga

A classical example is found in the final episodes of Stellvia of the Universe: the End of an Age of humanity living in fear of another (almost-)extinction and the Dawn of an Era of deep space exploration and, quite possibly, the more advanced aliens lending us hand. This new era was supposed to be covered in a Sequel Series but...

Comic Books

The three issue Comic Book Vimanarama has the epic of Ben Rama as real, with super science instead of magic. After the evil Ul-Shatan is defeated, the world is transformed with access to ancient philosophical truths, flying vimanas, vitamin laden air, prayer fueled refrigerators, and other marvels. The series ends with the hero rescuing three young idiots who crash a two man flying vimana into the bright face of the moon.
The first public appearance of Superman in the DCU. In most continuities, Superman is first introduced the world doing a dramatic save, giving the world something to hope for and kicking off the Age of Superheroes. (Or bringing back superheroes, in the Golden Age heroes are in continuity).
- Likewise, his return in Kingdom Come is this for everyone but The Narrator (who foresees that this will be a subversion instead). However, The Narrator talking down Supes in the end is the real dawn of an entirely new era.

Film

Close Encounters of the Third Kind has this with aliens bringing back humans abducted over several decades. It's been a while, but it's implied the aliens choose to stay and establish closer contact.

Literature

At the end of Clive Barker's Imajica comes the Reconciliation, allowing beings to travel freely between the five Dominions. People get used to this surprisingly fast.
The Lord of the Rings depicts the End of the Third Age and the passing of many things both evil and good, but it is also the beginning of the Fourth Age of Mankind—which need not be a Bad Thing.
The cycle of Arthurian mythology has this when Arthur draws the sword from the stone to become King, and the opposite trope when his power is broken at Camlann.
In Echoes of the Fourth Magic, nuclear war leads to an end of modern civilization. Angelic beings rescue some of the humans, however, and the world is born anew with magic and fantasy creatures.

Live Action Television

Star Trek First Contact: The crew of the Enterprise foil the Borg back in time and help Zefram Cochrane make his famous test flight of The Phoenix, the first warp-capable Earth craft. As a result, an alien ship detects the ship and decides to initiate first contact. When they appear from their landing craft and reveal themselves to be Vulcans, you know that Earth's time of planetbound turmoil and despair is over, and the planet's vibrant and hope-filled future as a space power has begun. Jerry Goldsmith's score complements it beautifully, too.
The Babylon 5 episode, "Into the Fire" where Capt. Sheridan leads a united force against both the Vorlons and the Shadows. Where at the beginning of the series, G'Kar notes the younger species of Humans, Narns etc. could no more interact with their predecessors than ants could with them, now Sheridan is able to tell two such god-like species to vamoose. Both races decide to leave, and the Third Age has begun where the younger species now live on their own terms, free of such godlike interference. This example mixes in a bit of sadness, as the departing Precursors take a great deal of wonder with them as well.
- As well as a bit of dread, now that the "grownups" are not around anymore to bail them out. Cue the Thirdspace movie, where they stumble upon a Sealed Evil in a Can that the Neglectful Precursors left behind.
- The very first words, spoken in voiceover by Londo Mollari at the opening of the pilot episode, were: "I was there at the dawn of the Third Age."
For an example that isn't an ending, the premise of Earth: Final Conflict is that aliens have come and helped transform the world for the better, offering solutions to famine, disease, and other ills free of charge. Not only were they not here To Serve Man, and more amazingly, we didn't attack these peaceful aliens. However; something fishy was afoot, and you don't want to know what. Trust us, it's better if you ignore seasons 2+.
2010: The Year We Make Contact ends as humanity is faced with incontrovertible proof that not only do Sufficiently Advanced Aliens exist, but they are aware of us and are capable of drastic action in the service of protecting life. In the film version, the closing narration makes it clear that this has motivated the nations of the world to end their conflicts.

Role Playing Game

Spirit of the Century treats the beginning 20th century this way (and, in it's Backstory, the dawn of each century, and millennia, for that matter).

Video Game

Final Fantasy X starts with an End of an Age and ends with this.
- As does Final Fantasy XIII. To elaborate, XIII covers the end of Cocoon, where fal'Cie ruled humanity and the birth of a new human civilization on Gran Pulse, free of fal'Cie (and particularly Lindzei's) rule.
The end of God of War III has this and an End of an Age. The age of Greek Myth, with its gods and monsters all dead, is over and the world is on the brink of ruin. Even the Fates are gone. But in his final moments, Kratos released the power of Hope, a power great enough to kill gods, to humanity. The survivors will be able to rebuild civilization free of the gods' influence and as masters of their own destiny.

Real Life

In Real Life some members of the Transhumanist movement believes that we currently live just on the brink of the Technological Singularity, which is to put an end to most problems that plague the modern society (but potentially create a ton of new ones), and usher the age of immortal, superhuman cyberminds.

Subversions

Anime and Manga

In Galaxy Express 999, the worlds of the Milky Way and Andromeda galaxies mostly see the Machine Empire's rising transhumanist New Order this way. Unfortunately for them.

Literature

In The Wheel of Time, this is combined with End of an Age; while the current Age is coming to an end, a new one is beginning, new Talents of the Power are being discovered, and vast advances in technology are being made. One character even lampshades it while watching a demonstration of the world's first ever firearm: "The world just changed in a very big way."

Theatre

In Pippin, Pippin becoming King is presented as the dawn of a more peaceful era in the song "Morning Glow," but this impression turns out to be mistaken.

Video Game

In Morrowind after the Player Character finally kills Dagoth Ur, he/she not only frees the inhabitants of Vvardenfell from nightmares, which were driving them insane and a corruption, which was slowly changing its victims via Body Horror, but also basically brings peace between fighting fractions. Even with two demi-gods dead, which means the End of an Age for the Tribunal, Vivec still decides to disband the religious police and use his divine power to help these in need. Everything should be wonderful from this point on, right? It turns out that stripping Vivec of from his powers causes the Ministery of Truth to fall and Red Mountain to erupt, not even a century after the events of the game.
The great conflict of Golden Sun: The Lost Age, over whether to restore the power of Alchemy to the world and risk it falling into the hands of evildoers or to let the world rot without Alchemy, is ultimately resolved in favor of restoring Alchemy by the heroes. The Lost Age ends on a relatively hopeful note: the parents come back, Alex's plans to gain the power of the Golden Sun are thwarted, and now the world can return to its former glory, right? Golden Sun: Dark Dawn begins thirty years later and stars the Spin Offspring... fighting new evils powered by Alchemy and newly-restored ancient Magitek.
The ending of Kingdoms of Amalur sees the end of Fate. Together with the surge of magical potential among the mortal races marks the beginning of the Age of Heroes. It's not all good news though. The Fae and their magic are also slowly fading from the world. The Great Cycle has been broken, rendering them mortal for all intents and purposes. Many of the Fae encountered in-game know all too well that their time has passed.