Have you ever felt like getting some people together and toasting something in the name of science? If you have, then you may have already noticed that of the eleven federally recognized U.S. holidays, not a one of them has anything to do with science.

There are, of course, many unofficial days of observance throughout the year, but how many science-themed examples can you really name off the top of your head, save the obvious Earth day and Arbor Day? Let us help you out — here are 10 scientific holidays to look forward to in 2012 and beyond.

10) Yuri's Night: April 12, 2012
Yuri Gagarin was a soviet pilot, cosmonaut, and the first person in history to venture into outer space. In recognition of his bad-assery, people the world over congregate every year on April 12th to commemorate his flight in the Vostok 1 spaceship (April 12, 1961), the first Space Shuttle flight (April 12, 1981), and to promote the future of space exploration. [Image via]

Last year marked the 50th anniversary of Gagarin's voyage to outer space, but people have been celebrating every year since 2001, and there's no sign of them letting up in the future. Yuri's Night Space Parties are held every year in cities and towns all over the world (the photo featured here was captured at the Yuri's Night Bay Area 2010, held at NASA Ames Research Center in California). Head over to the main Yuri's Night webpage to keep up-to-date on where to find a local celebration as the date approaches. [Photo by Matthew Reyes]

9) Pi Day: March 14, 2012
The mathematical constant pi (or π) represents the relationship between a circle's diameter and its circumference. Most people know pi from equations like A = πr2, which is used to calculate the area of a circle, but even beyond widely-known area and volume equations, pi is one of the most useful and commonly used constants in all of mathematics.

While pi has been calculated to over 10 trillion digits past its decimal point, it is typically just approximated as 3.14, which is why pi day is celebrated every year by maths buffs the the world over on the fourteenth day of March, the third month of the year (fun fact: pi day also happens to be Albert Einstein's birthday). You can celebrate this year by kicking back with a slice of pie, listening to some pi-inspired tunes, and getting your needlework on. Learn more on the official pi day website.

8) Pi Approximation Day: July 22, 2012
And for those who choose to laugh in the face of pi's irrational nature by simply equating it to 22/7 (an over-approximation, but a rational number, nonetheless), there is Pi Approximation Day, which is observed on July 22 (22/7 in day/month date format).

7) National Metric Week: October 7—13, 2012
The metric system is used by every single industrialized country on Earth but the United States, and its use is indispensable to just about every scientific field imaginable.

Fight the good fight, people — recognize the superiority of the metric system on the second week of October, during National Metric Week (in other words, the week containing 10/10) — and maybe one day we'll recognize it every day of the year. Familiarize yourself with the switch to metric with handy guides like this one, courtesy of XKCD.

6) Mole Day: October 23, 2012
The "mole" is one of the most basic units of measurement in all of chemistry. Generally speaking, one mole of any substance — be it an atom like hydrogen, or a molecular compound like water — is said to comprise 6.02 x 1023 atoms or molecules of that substance. This numer is known as Avogadro's number, in recognition of Amedeo Avogadro (pictured here with a mole on his shoulder), who conceived of the constant.

In commemoration of Avogadro's number, chemistry enthusiasts celebrate annually on October 23 from 6:02 am to 6:02 pm (though the nature of Avogadro's number means alternate observance dates — like June 2 — also exist). Chemists have been celebrating mole day unofficially every year since 1991 — you can learn more about this year's celebrations — including this year's theme of "Molar Eclipse" — over at the National Mole Day Foundation. [Image via]

5) Hagfish day: October 17th, 2012
Hagfish are utterly repulsive creatures, but they're also pretty amazing, and play an important role in their native ecosystems. It was with this in mind that Ruth Musgrave, director of WhaleTimes.org, introduced Hagfish day in 2009.

"In general, science programs highlight the cute," said Musgrave — a former marine science educator and freelance children's writer — in an interview with Science Magazine," but an ecosystem needs everything." The idea behind Hagfish Day, she explains, is that "repugnant and slightly revolting animals like hagfish make great role models for highlighting conservation concerns for all marine animals."

Hagfish Day is celebrated the third Wednesday of every October. Visit WhaleTimes.org for more info, including suggestions on how to observe the holiday like a slime-loving pro.

4) International Darwin Day: February 12, 2012
Created in 1993 by molecular biologist Robert Stephens, Darwin Day is billed as a global celebration of science, humanity, and reason, and is held every year on or around February 12th — the birthday of evolutionary biologist Charles Darwin. According to the International Darwin Day Foundation website:

Recognizing science as an international language accessible to all individuals and societies, the International Darwin Day Foundation provides a new global holiday that transcends separate nationalities and cultures. Darwin Day can be celebrated in many different ways: civic ceremonies with official proclamations, educational symposia, birthday parties, art shows, book discussions, lobby days, games, protests, and dinner parties. Organizers may include: academic societies, science organizations, freethought groups, religious congregations, libraries, museums, galleries, teachers and students, families and friends. In Darwin Day, we are able to recognize the diversity among us, while celebrating our common humanity and the universal understanding we share.

3) DNA Day: April 20, 2012
Historically, DNA Day has been celebrated on April 25th. It was on April 25th, in 1953, that the article on the structure of DNA (based on the work of James Watson, Francis Crick, and Rosalind Franklin) was first published; and it was also during April (fifty years later in 2003) that the Human Genome Project was completed.

It was also in 2003 that the U.S. Senate and the House of Representatives declared the month of April "Human Genome Month," and the 25th "DNA Day" (they did not, however, make it an official, annual holiday). Every DNA Day since then has been organized by the National Human Genome Research Institute (NHGRI), with the holiday taking place on different days throughout April. This year's celebrations will be held on April 20th — check out the official DNA Day webpage to learn more. [Image via]

2. Square Root Day: April 4, 2016
It probably doesn't really need explaining, but Square Root Day is held whenever the numbers corresponding to the month and the day are equal to the square root of the last two digits of the year — that means the next Square Root Day won't actually come around until 4/4/2016. HOWEVER — square root days only happen nine times every century, and the distribution of the days is such that the years between successive square root days within each century are consecutive odd numbers.