Links to the Breadcrumb trail
- PMN Policy
- PMN news
Author of the article:
Content of the article
THE CONVERSATION
This article was originally published in The Conversation, an independent and non-profit source of news, analysis and commentary by academic experts. Disclosure information is available on the original site.
——
Author: Samantha Lawler, Assistant Professor of Astronomy, University of Regina
Curious Kids is a series for children of all ages. Do you have a question that you would like an expert to answer? Send it to CuriousKidsCanadaâ † * theconversation.com.
Why does it matter if Pluto is a planet or a dwarf planet? Because for me, it just makes it more confusing in our solar system. I know that some things in space are planets, others are stars, and some are other names like moons or comets. The dwarf planet is a different name and I think it just makes it more confusing. –
Advertising 2
This ad is not yet loaded, but your article continues below.
Content of the article
Timmy, 11, Kitchener, Ont.
“Comet”, “star” and “planet” are names of categories that immediately tell you something important about what they describe.
Our solar system consists of the sun, planets (which orbit the sun) and small bodies (which either orbit the sun or planets). The “small bodies” category is divided into even smaller categories, mostly depending on the shape and size of the orbits.
In 1801, astronomers discovered Ceres, which was originally categorized as a “planet.” Astronomers measure that it is much smaller than other known planets. Much smaller objects were soon discovered in orbits very close to Ceres. These small bodies were categorized as “asteroids” and we have since found hundreds of thousands of them in the asteroid belt.
Advertising 3
This ad is not yet loaded, but your article continues below.
Content of the article
New discoveries
A similar process of discovery and re-categorization occurred for small bodies further in the solar system.
Pluto was discovered in 1930 and has been called the ninth planet in our solar system for many decades. But astronomers soon learned that Pluto is quite different from the other eight planets: it is in an inclined orbit and is much smaller than the other planets.
Over the years, astronomers have discovered more and more small, planet-like objects that cross Pluto’s orbit. They are now categorized as “Kuiper Belt objects.” It increasingly seemed that Pluto could fit better into the category of objects in the Kuiper Belt than with the planets.
In 2005, a new Eris object was discovered in the outer solar system, which is even heavier than Pluto. This has led astronomers to consider whether both Eris and Pluto are planets or not. Astronomers thought it was an important enough decision for the International Astronomical Union to vote on it in 2006. Astronomers decided that instead of lowering Pluto to a simple old object from the Kuiper Belt, they would make a new category of small bodies called the dwarf planet. Pluto and Eris will be part of this new category.
Advertising 4
This ad is not yet loaded, but your article continues below.
Content of the article
How planets form
Solar systems like ours are formed by large clouds of dust and gas that collapse into disks around young stars, but astronomers are still learning exactly how this process works. We use telescopes to look closely at the formation of solar systems far away, but they are so far away that it is really difficult to see how planets form directly.
The planetesimal – a baby planet – is first formed by lumps of dust in a disk orbiting a young star. Then the planetesimals grab the nearby pebbles, dust and sometimes even smaller planetesimals with their gravity, which becomes stronger as they get bigger. When they reach several hundred kilometers in diameter, they have enough gravity to pull in a round shape, which is the definition of a dwarf planet.
Advertising 5
This ad is not yet loaded, but your article continues below.
Content of the article
Measuring small bodies in our solar system, including dwarf planets, and comparing them to computer simulations is another way to see how our solar system formed. Our current theory is that there must have been many dwarf planets that formed in our solar system.
Ceres, the asteroid belt, as well as Pluto, Eris, and about a dozen other objects in the Kuiper belt are large enough to be in the category of dwarf planets. This means that although they are planetesimals that have grown large enough to be round, they have not developed gravity strong enough to catch all other planetesimals close to their orbit.
Other solar systems
Astronomers have now measured more than 5,000 exoplanets, planets in other solar systems. We won’t be able to measure dwarf planets there for very long, but those we’ve found in our own solar system can teach us how planets form everywhere.
Advertising 6
This ad is not yet loaded, but your article continues below.
Content of the article
——
Hello curious children! Do you have a question that you would like an expert to answer? Ask an adult to send your question to CuriousKidsCanadaâ † * theconversation.com. Please tell us your name, age and city where you live.
And since curiosity has no age limit – adults, let us know what you are wondering. We will not be able to answer every question, but we will do our best.
Samantha Lawler receives funding from the Natural Sciences and Engineering Research Council of Canada.
——
This article was republished by The Conversation under a Creative Commons license. Disclosure information is available on the original site. Read the original article:
Share this article on your social network
Advertising
This ad is not yet loaded, but your article continues below.
NP Published
Sign up to receive daily top stories from the National Post, a division of Postmedia Network Inc.
By clicking on the register button, you agree to receive the above newsletter from Postmedia Network Inc. You can unsubscribe at any time by clicking the unsubscribe link at the bottom of our emails. Postmedia Network Inc. | 365 Bloor Street East, Toronto, Ontario, M4W 3L4 | 416-383-2300
Thank you for registering!
Email is welcome. If you don’t see it, please check your junk folder.
The next issue of NP Posted will be in your inbox soon.
There was a problem registering with you. Please, try again
Comments
Postmedia is committed to maintaining a lively but civic discussion forum and encourages all readers to share their views on our articles. It can take up to an hour to moderate comments before they appear on the site. Please keep your comments up to date and respectful. We have enabled email notifications – you will now receive an email if you receive a response to your comment, there is an update on the comment thread you follow, or if a user you follow comments on comments. Visit our Community Guidelines for more information and details on how to adjust your email settings.
Add Comment