3: One of the year's best meteor showers, the Quadrantids, appears, visible to skygazers in the northern hemisphere.
5--8: The latest electronics and tech gadgets are unveiled at CES in Las Vegas.
13: Nintendo reveals more about its new offering Switch, a video-game console that doubles as a handheld gaming gadget.
28: The highly anticipated sequel to the BBC nature documentary Planet Earth hits U.S. television screens.
1: Cardiovascular health is brought to the fore as doctors draw attention to American Heart Month.
16--20: Top researchers present game-changing science at the American Association for the Advancement of Science's annual meeting.
27: Tech fans descend on Barcelona for the Mobile World Congress, where smartphone companies reveal their latest wares.
TBD: Samsung is expected to unveil its next Android-powered iPhone rival.
10--19: Entrepreneurs, investors and tech fans gather in Austin for the annual SXSW festival, which is where companies like Twitter and Foursquare got their start.
20: Spring begins in the northern hemisphere; autumn begins in the south.
TBD: NASA astronaut Jack Fischer and Russian cosmonaut Fyodor Yurchikhin blast to the International Space Station.
TBD: The disappearing-photo app Snapchat is expected to become part of a publicly traded company in a hotly anticipated IPO.
TBD: Filmmakers show off their latest aerial shorts at the New York City Drone Film Festival.
TBD: SpaceX's three-engine Falcon Heavy rocket, designed to carry humans to the moon and beyond, is expected to have its maiden flight.
18--19: Facebook shows off its latest offerings, from virtual reality to drones, at its annual F8 conference.
22: Environmentalists across the globe celebrate the 47th Earth Day.
24--28: Some of the world's top thinkers share their genius at TED, which is in Vancouver this year.
28: Thousands of students flock to Washington to learn about space exploration, marine biology and other careers at the X-Stem Extreme Stem Symposium.
10--12: Windows fans get a peek at upcoming updates at the annual developer conference Microsoft Build.
28: Amateur photographers and tourists flock to New York City for Manhattanhenge (above), a phenomenon in which the sunset perfectly aligns with Manhattan's street grid.
TBD: The search giant unveils its latest software and gadgets at Google I/O.
TBD: U.S. language prodigies face off in the Scripps National Spelling Bee finals.
30: The world's most influential tech leaders gather in California to discuss the future of the industry at the Code Conference.
1: Dozens of new emojis are unveiled to help enliven your text-message game.
1: Hurricane season starts over the Atlantic Ocean.
13--15: Gamers of all stripes land in Los Angeles for E3, the year's top video-game convention.
15: Cellular roaming charges are abolished in the E.U., easing the costs that come with cross-border travel.
19--25: Boeing, Airbus and other aerospace firms show their latest jetliners at the International Paris Air Show, the world's foremost aviation gathering.
21: Summer begins in the northern hemisphere; winter begins in the south.
29: Happy birthday to you, iPhone. The Apple device turns 10.
22--30: Computer hackers from around the world gather in Las Vegas for the Black Hat and DEFCON digital-security conferences.
23--29: Green-thumbed researchers convene in Shenzhen, China, for the XIX International Botanical Congress.
28: For World Hepatitis Day, the World Health Organization urges people to get vaccinated.
14--16: Researchers share big ideas about little machines at Barcelona's Global Conference on Nanotechnology.
21: Stargazers flock to towns like Hopkinsville, Ky., for the best view of a rare total solar eclipse, one of the most spectacular shows in the sky.
22--26: Video-game makers try to one-up one another with their latest creations at Gamescom in Cologne, Germany.
1--6: Electronics companies from across the world gather in Berlin to flaunt their latest gizmos.
7: Apple is expected to unveil a radical new iPhone, rumored to have a curved screen design.
15: NASA's Cassini probe crashes into Saturn (on purpose) to protect its moons from earthly bacteria.
22: Autumn begins in the northern hemisphere; spring begins in the south.
27: The world's smartest teens compete for top honors in the Google Science Fair, a global online science showdown.
1: Global charities raise awareness--and cash--during National Breast Cancer Awareness Month.
TBD: British fighter pilot Andy Green (above) tries to break his own land-speed record in a rocket- and jet-powered vehicle called the Bloodhound SSC.
TBD: The Nobel Prizes in science are announced, recognizing the most significant advances in chemistry, physics and medicine.
TBD: Apple and Google are expected to launch new versions of their Mac and Android software.
13: Planet spotters find Venus and Jupiter just 0.3 degrees apart in the night sky, a rare gathering of the two bodies.
TBD: Competitive hopefuls in countless categories will vie for spots in Guinness World Records.
1: World AIDS Day raises awareness about HIV treatment and prevention, and highlights progress made around the world.
14: The Geminid meteor shower produces about 100 shooting stars an hour for those in the northern hemisphere; search for the constellation Gemini for the best view.
21: Winter begins in the northern hemisphere; summer begins in the south.
31: The earth's population is expected to top 7.4 billion for the first time.
TBD: Russian billionaire Yuri Milner's Breakthrough Prizes are awarded for advances in life sciences, physics and mathematics.
TBD: Microsoft releases Project Scorpio, its most powerful Xbox video-game console to date.
Compiled by Lisa Eadicicco