Thousands of people turn out around the world for the March for Science - here are the photos

David Zalubowski/APAnaleigh Belisle of Fort Collins, Colo., holds a sign before a march for science Saturday, April 22, 2017, in DenverScientists and their supporters are taking to the streets in more than 400 cities and towns around the world on April 22 - Earth Day - to voice their support for the value of scientific inquiry.

The March for Science is expected to draw tens of thousands at its main event on Washington DC's National Mall. The day started with teach-ins and a rally, and the march will proceed from the Washington Monument grounds to Union Square at 2 p.m. Satellite marches are taking place throughout the day in cities like New York City, London, Sydney, Hong Kong, and Sao Paulo.

The stated goals of the march are to affirm science as a crucial part of a strong democracy, show support for the scientific community, and highlight the value of fact-based inquiry and policy-making. Organizers say the march is not a partisan event, but a large-scale organized action like this is by nature somewhat political - a reality that led some in the scientific community to distance themselves from the event.

Here's what the marches look like around the world: