The Asteroid Belt

The majority of asteroids in the solar system are found in the area of space between the orbits of Mars and Jupiter, this is known as the asteroid belt. The belt is 2.2 - 3.2 astronomical units (AU) from the Sun and is about 1 AU thick.

The Kuiper Belt

Composed primarily of small solar system bodies made mostly of ices the Kuiper Belt is roughly 30 - 55 AU from the Sun. The ices are frozen volatiles (gases) such as methane, ammonia, nitrogen and water. It also is home to the known dwarf planets Pluto, Haumea and Makemake.

The Oort Cloud

The Oort Cloud is an extended shell of icy objects that exist in the outermost reaches of the solar system. The inner limits of the Oort Cloud begin at about 2,000 AU from the Sun. The cloud itself stretches out almost a quarter of the way to the nearest star, Proxima Centauri. 

Illustrations by Laurine Moreau

Ceres is the closest dwarf planet to the Sun and is located in the asteroid belt, making it the only dwarf planet in the inner solar system. Ceres is also the smallest of the bodies currently classified as dwarf planets.

Image credit: NASA, based on the planet profiles by Space Plasma

Pluto is the second closest dwarf planet to the Sun and is also the second most massive dwarf planet. It is possible that either Pluto is the largest dwarf planet but Pluto’s atmosphere makes it is difficult to determine a precise size. Pluto was discovered on February 18th, 1930 by Clyde W. Tombaugh at the Lowell Observatory.

Image credit: NASA, based on the planet profiles by Space Plasma


Coming soon:, launched by entrop-e, shychemist, and geogallery, is Tumblr’s project for promoting science education around the world.

At SciNote, we believe that science shouldn’t just be reading about the ideas of people with PhDs and Nobel Prizes. We believe that science is an active process of asking questions and finding answers.

That’s why we, at SciNote, want to hear from you. We want to ponder the interesting questions you pose and get excited with you over the cool science you see in your world.

SciNote will feature the best of the Tumblr science community, and we will compile and publish the top posts from every year in the form of a magazine available both digitally and in print. Think of SciNote magazine as the Tumblr science magazine.

We hope to celebrate our launch by featuring some of the coolest science from around Tumblr. So before we launch SciNote, we would like to collect 25 science posts and/or questions from you, including:

  • the most interesting science news you have come across
  • questions you’ve always wanted to ask
  • fascinating facts that you’ve learned
  • pictures of nature and/or science that you’ve taken
  • cool research that you’ve participated in
  • any other science-related thing you’d like to tell us!

So please:

  1. Submit posts or ask questions to be featured on our blog and for an opportunity to be published in SciNote magazine.
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  4. If you’re interested, apply to join our staff here.
  5. Reblog this post so that we can collect 25 posts and launch our project as soon as possible!

Thank you all and happy science!

(via spaceplasma)

Google doesn’t know what Uranus looks like

  1. Comet C/2001 Q4 (NEAT) (source)
  2. Comet Schwassman-Wachmann 3 breakup (source)
  3. Comet Lovejoy (source)
  4. Comet ISON (source)
  5. Comet Tempel 1 Deep Impact (source
  6. Comet 67P/Churyumov–Gerasimenko from Rosetta Probe (source)
  7. Comet 67P/Churyumov–Gerasimenko Surface (source)
  8. Comet Hale Bopp (source)
  9. Comet McNaught over the Pacific Ocean (source)
  10. Comet Holmes (source)

Mercury: 87.97 days (0.2 years)
Venus : 224.70 days (0.6 years)
Earth: 365.26 days(1 year)
Mars: 686.98 days(1.9 years)
Jupiter: 4,332.82 days (11.9 years)
Saturn: 10,755.70 days (29.5 years)
Uranus: 30,687.15 days (84 years)
Neptune: 60,190.03 days (164.8 years)