As another year comes to an end, it’s both impressive and encouraging to look back at 2016’s scientific advancements that have provided a deeper understanding of how our world works. Here’s a look at 10 of the biggest, most important discoveries.

1) Einstein’s gravitational waves were found

A hundred years ago, in 1916, renowned genius Albert Einstein published his theory of gravity, which included the existence of gravitational waves. In February, researchers at the Laser Interferometer Gravitational-Wave Observatory, or LIGO, detected a fleeting signal from gravitational waves released by a pair of colliding black holes. Four months later, they detected the waves again.

2) Proxima b, or the new Earth, was found

Perhaps the biggest space news of the year was the discovery of Proxima Centauri b, or Proxima b, which was hailed as the most Earth-like planet ever discovered. It lies within the “habitable zone” in the Proxima Centauri solar system, which is particularly exciting because it’s the closest system to the Milky Way. One of the most Earth-like qualities of Proxima b is that it’s roughly Earth-sized. Because the planet is closer to its moon, however, it has a steep temperature gradient between the two hemispheres. The tight orbit of the planet may cause it to be exposed to deadly radiation, rough winds and no atmosphere.

3) The Zika Virus

Image courtesy Thinkstock

Starting in Brazil – home of the 2016 Summer Olympics – the Zika Virus was the health scare of the year, and it canceled many travel plans as new cases were found in more than 70 countries. The virus was particularly dangerous for mothers because it has been linked to the birth defect microcephaly – a rare neurological condition in which a baby’s head is much smaller than normal.

4) Babies could have three people involved in their conception

The United Kingdom has made mitochondrial replacement therapy (MRT) legal. The treatment helps reduce the risk of a mother passing genetic diseases on to her child. The therapy involves exchanging the mitochondria in the egg of the mother with the healthy mitochondria of a donor. The baby genetically has two parents but also has mitochondria from the donor. The first healthy baby was born using this procedure earlier this year in Mexico.

5) Artificial Intelligence had a big win

A computer program named AlphaGo beat the 18-time world champion Lee Sodul at Go, a Chinese board game, in March. The game is notoriously difficult as it has billions of potential board arrangements, making the accomplishment of the AI program significant. Google’s AI division, DeepMind, created the program. AlphaGo learned the game by using neural networks and playing against human experts and itself.

6) A change in how humans migrated

The process of humans migrating out of Africa was discovered to be more complex than originally thought. Several studies released in 2016 showed that humans migrated out of Africa at a variety of times to several destinations. Stone tools in India suggest members of the Homo genus reached Asia 2.6 million years ago, 500,000 years earlier than previously predicted. Another study found humans and Neanderthals interbred about 40,000 years earlier than originally estimated.

7) A dinosaur tail was found preserved in amber

A scientist discovered a dinosaur’s tail from 99 million years ago. The tail, which was preserved in amber, has bones, soft tissue and feathers. It belongs to a juvenile coelurosaur. The feathers appear to be decorative, leaving the dinosaur incapable of flight.

8) Arctic sea ice at an all-time low

In late October, scientists measured Arctic ice at a historic low. Air temperatures also are at record highs. The long-term consequences are unknown, but will be significant according to experts. They predict the ice may run out in the next few decades. The recovery rate for the ice was slower than predicted this year.

9) SpaceX lands rocket in ocean

Image courtesy SpaceX

In early April, SpaceX successfully landed a rocket on a ship in the ocean. It was their first time landing on a moving target and their fifth attempt. It was a major step toward SpaceX’s goal of space exploration.

10) Gene-editing was successfully done in a human

Scientists at Sichuan University in China successfully fought cancer by using Crispr gene editing in white blood cells and transferring them into a patient suffering from metastatic lung cancer, a first-time use in humans. People worry that this breakthrough in gene editing could have moral consequences and lead to designer babies.