Final answer:
In a timeline from the oldest to most recent: The Big Bang, formation of elements like carbon and oxygen, start of nuclear fusion in the Sun, earliest life on Earth, dinosaurs go extinct, and earliest humans appear.
Step-by-step explanation:
To rank the events based on when they occurred from longest ago to most recent:
- The Big Bang & the universe begins to expand: This is the oldest event, occurring around 14 billion years ago. It marks the beginning of the universe and the start of its expansion.
- Elements such as carbon and oxygen first exist: These elements are created within stars through nuclear processes. It took billions of years after the Big Bang for stars to form and to forge these heavier elements.
- Nuclear fusion begins in the Sun: Our solar system, including the Sun, formed about 5 billion years ago. Nuclear fusion began in the Sun's core, allowing it to shine and provide energy.
- Earliest life on Earth: The first signs of life on Earth date back to approximately 3.5 billion years ago.
- Dinosaurs go extinct: This happened about 65 million years ago and represents a more recent event in the cosmic calendar.
- Earliest humans: Anatomically modern humans appeared roughly 300,000 years ago, making this the most recent event on the timeline.
The Big Bang and subsequent formation of hydrogen and helium set the stage for stellar evolution, which in turn led to the chemical evolution of the universe, culminating in the formation of the elements necessary for life. Life on Earth, followed by the extinction of the dinosaurs, and eventually the emergence of humans, are all major milestones. The time scales for these events vary vastly, with the formation of the universe at the grand outset and the appearance of humans as a rather recent occurrence.