Sun. Feb 25th, 2024
the origin of the planets

In our previous post we looked at star formation from condensed balls of gas within interstellar nebulae to the formation of open clusters of hundreds of sister stars using images taken from Killarney Provincial Park observatories.

In this post, we will discuss how planets and life emerged from the debris of star formation.

The formation of planets.

Astronomers believe that our early solar system was made up mainly of gas, dust and ice left over from the formation of the Sun.

protoplanetary diskProtoplanetary disk around the star HL Taurie. Credit: ALMA (ESO/NAOJ/NRAO)

Over time, a protoplanetary disk, like the one shown above, would have formed around our own Sun. Like all protoplanetary disks, ours was created by the gravity of a central star spinning material at such great speeds. that all the material in orbit fell into a thin disk. In such accretion disks, larger bodies are formed by the collision of trillions of bits of smaller ones.

This process led to the formation of, at first, smaller planetesimals and then, from them, planets and asteroids. In the far reaches of the solar system, icy, rocky debris became comets and Kuiper Belt objects.

The solar system takes shape

During the dawn of our solar system, there may have been dozens of planets orbiting the Sun. Through destructive collisions, some of these planets destroyed each other until reaching the eight officially recognized today.

MoonThe Moon photographed by the 0.41 meter telescope in the Kchi Waasa Debaabing dome of the Killarney Provincial Park Observatory Complex.

These collisions may have occurred throughout the solar system and close to home.

One promising theory is that an ancient Mars-sized planet, known as Theia, collided with our early Earth, known as Gaia, to produce the Earth/Moon system we know today.

Looking outward to learn about the Earth

Studying the planets as we see them today tells us a lot about the formation of the Earth, its behavior, and its possible future.

On some terrestrial planets (Mercury, Venus, Earth, and Mars), volcanoes and plate tectonics (probably driven by residual heat from the protoplanetary disk, frictional heating, and radioactive decay) helped shape the continents and the mountain ranges.

Water and ice brought to us by comets, asteroids, and volcanic activity helped create an atmosphere and erosive forces. The nitrogen that makes up 78% of our atmosphere originated in our protoplanetary disk, which, in turn, received excess nitrogen from stars that lived and died long before the Sun (see previous article).

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view of marsThe planet Mars photographed by the 0.41 meter telescope in the Kchi Waasa Debaabing dome of the Killarney Provincial Park Observatory Complex

In the image of Mars (above), we can see:

  • Its south polar cap (at the bottom)
  • A bluish-white haze around its north pole (at the top)
  • A gigantic rift valley, known as Valles Marineris (center right)
  • A large volcano, known as Olympus Mons (center left)

New observations by robotic spacecraft and landers are beginning to reveal fascinating details about the possible history of Mars and what that could teach us about the evolution of our own planet.

An early warning about climate change

Today, we are all very concerned about human-made greenhouse gases and their impact on climate change.

The concept that greenhouse gases have an impact on planetary temperatures is not new. Only a small amount of greenhouse gases are needed to keep our planet at a comfortable temperature.

However, the idea that excess greenhouse gases can cause massive warming crystallized in the 1960s. The now famous astronomer Carl Sagan observed evidence of the greenhouse effect on Venus which, in turn, gave us an early warning. of what we could face in the future if we do not reduce our greenhouse gas emissions.

Image of VenusImage of the Mariner 10 spacecraft from the planet Venus. Credit: NASA/JPL-Caltech

Venus’ greenhouse gas mix is ​​so significant that it makes it the hottest planet in the solar system, although it is almost twice as far away and therefore receives four times less heat from the Sun than Mercury.

Impact Events: The Liberators of Life and Death

After the main planets formed, there were still a large number of remnants of icy asteroids and comets.

Most would be dispersed by the gravitational pull of the Sun or Jupiter to the edge of our solar system. However, some came close enough to impact Earth.

These impacts would have been both beneficial and destructive to life. Life may have benefited from the introduction of water and organic compounds to our planet. Of course, the destructive effects are obvious in that the impacts would destroy most life in the immediate area, if not to a greater extent, throughout the world.

Aerial image of the Sudbury Basin.Image credit: NASA Earth Observatory. Schematic of the Sudbury Basin impact crater based on research by: Hudyma, Marty and Beneteau, Donna. (2010). Sudbury Regional Seismic Network.

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The image above shows the billion-year-old comet impact (in blue) that formed the Sudbury Basin and the 37-million-year-old asteroid impact (in green) that formed Lake Wanapitei. The city of Sudbury is at the bottom center of this image.

A meteorite crater from Ontario parks

Did you know that Ontario Parks has its own meteorite crater?

Aerial image of Algonquin's Brent Meteorite CraterBrent Meteorite Crater in Algonquin Provincial Park. Image credit: Microsoft Bing Maps

The Brent Meteorite Crater located in the northern part of Algonquin Park is an extraordinary impact crater that was created about 400 million years ago.

The explosion that resulted from this impact is estimated to have generated the equivalent of 250 megatons of TNT, or approximately 5 times larger than the largest hydrogen bomb ever detonated on Earth.

The cosmic connection with our parks and with ourselves

We have learned a lot about the history of our Universe from its beginnings in the Big Bang to the formation of our planet, and we have only had time to scratch the surface of discoveries in these areas.

Now is the time to bring together all our learnings and weave a story of our existence from what we have discussed.

Our Ontario provincial parks are a beautiful backdrop to the theme of Earth’s cosmic origins.

Sunset over the lake

The carbon in the trees and the silicon in the rocks came from the remains of stars and supernovae. The distant mountains were formed by tectonic activity, driven, at least in part, by energy from the protoplanetary disk. The water in the lakes may have originated in the first comets and/or asteroids. The vibrant sky stems from our nitrogen-rich atmosphere and a recent volcanic eruption.

Lake fish and sky birds have common ancestors formed from organic compounds that may have been brought to Earth many eons ago. Finally, the hemoglobin in your blood, and the blood of all your loved ones, came from the cores of ancient stars that went supernova.

Paraphrasing wise words from Carl Sagan and William Shakespeare, We are the stuff that stars are made of and, therefore, we are children of the Cosmos.. As such, we have a strong interest in applying the lessons of the cosmos to the management of our planet.

We owe it to ourselves and the Universe to protect our planet by learning, listening and acting to protect it for future generations.

Do you want to continue reading?

To continue the story of our astronomical origins, here are the other installments of From the Big Bang to our provincial parks and beyond:

Note: Unless otherwise noted, all astronomical images used for this series were taken with the equipment at one of our two observatories in Killarney Provincial Park; Waasa Debaabing, “see far (as far as the eye can see)” and Kchi waasa Debaabing, “see far away (as far as the eye can see).”