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Astronomy: Evaluating sources

How to evaluate whether your sources are reliable: the P.R.O.V.E.N. test

Use the P.R.O.V.E.N. Source Evaluation Process to help you determine whether the sources you find are credible and appropriate choices for your particular research purpose. The questions below will help you think critically during the source evaluation process:

  • Purpose: How and why the source was created. Why does this information exist, why is it in this form (book, article, website, etc.), and who is the intended audience? Is the purpose clear?
  • Relevance: The value of the source for your needs. How useful is this source in answering your question, supporting your argument, or adding to your knowledge? Is the type and content of the source appropriate for your assignment?
  • Objectivity: The reasonableness and completeness of the information. How thorough and balanced is this source? Does it present fact or opinion? How well do its creators acknowledge their point of view, represent other points of view fully, and critique them professionally?
  • Verifiability: The accuracy and truthfulness of the information. How well do the creators of this source support their information with factual evidence, identify and cite their sources, and accurately represent information from other sources? Can you find the original source(s) of the information or verify facts in other sources? What do experts say about the topic?
  • Expertise: The authority of the authors and the source. Who created this source and what education and/or professional or personal experience makes them authorities on the topic? How was the source reviewed before publication? Do other experts cite this source or otherwise acknowledge the authority of its creators?
  • Newness: The age of the information. Does your topic require current information? How up-to-date is this source and the information within it? 

Caulfield, Mike. "Four Moves and a Habit." Web Literacy for Student Fact-Checkers, 2017.

P.R.O.V.E.N. Source Evaluation by Ellen Carey (6/18/18) is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

What top-level domain names reveal about websites

A link or url tells you quite a bit about where the information on the page comes from and who the intended audience is. The last three letters of a url (uniform resource locator) or link will tell you a great deal about who owns a website, who writes the content and what their purpose is. To find out more about a website, check it on Whois.

Top-level domain

Abbreviation for:

Who uses it Url of example website


commercial commercial entities


education universities and colleges


government U.S. government


network network infrastructure


organization nonprofit organizations


military U.S. military

Compare these three sites about astronomy or space

Compare these three websites about space and astronomy.

Link Purpose Reliability Objectivity Verifiability Expertise Newness                  
  1. What is the TLD (top-level domain; e.g., .com, .org or .gov) and what does it tell you about the authors and the audience?
  2. To find the purpose, look for a page titled About Us or Mission.
  3. To verify the newness of a website, scroll to the bottom of the page to find a "last updated date" or a year next to the copyright symbol, ©2021, for example. If there is no date at the bottom, click on any link on the homepage to find an article or current page that does have a date on it.

Evaluating websites

Click on each link to discover who the author is and run it through the P.R.O.V.E.N. test.

Link (find domain name) Purpose Reliability Objectivity Verifiability Expertise Newness
A link to a website            
Another link            
Also a link            
Here's another            
And finally