![Condensation on the window of the Apollo 12 Lunar Module, November 1969](/sites/default/files/styles/resource_card_image_360x300_/public/2019-12/Condensation_window_Apollo_12.jpg?itok=KtlUs1RV)
Humidity on Earth and on the ISS
Backgrounders
Humidity is an important part of life on Earth and life in space. This backgrounder explains what humidity is, how it is measured and how it affects us both mentally and physically.
![How can I write secret messages?](/sites/default/files/2019-08/how-can-i-write-secret-messages.jpg)
How can I write secret messages?
Hands-on Activities
Learn how you can write and reveal secret messages in this hands-on chemistry activity.
![How does rain become acidic?](/sites/default/files/2019-08/how-does-rain-become-acidic.jpg)
How does rain become acidic?
Hands-on Activities
Learn how to make a pH indicator and test water samples.
![Goldfish Goldfish](/sites/default/files/styles/resource_card_image_360x300_/public/Gullfiskur.jpg?itok=L6czSzoc)
Fish: Freshwater
Picture Collections
4 images of some fish such as koi that live in freshwater river and lake environments and in freshwater aquariums and garden ponds
![Clown Fish Clown Fish](/sites/default/files/styles/resource_card_image_360x300_/public/Clown_fish_in_the_Andaman_Coral_Reef.jpg?itok=nkTzBh1T)
Fish: Saltwater
Picture Collections
14 images of some fish such as lion fish, grouper and sharks that live in saltwater environments like oceans, saltwater lakes and aquariums
![Salmon aquaculture pens](/sites/default/files/styles/resource_card_image_360x300_/public/2020-05/Salmon_aquaculture_pens.jpg?itok=yrwdnv2j)
Farmed Salmon vs. Wild Salmon
STEM Explained
Aquaculture is seen as a sustainable way to produce fish. But are farmed salmon better than wild fish?
![Massive algal bloom](/sites/default/files/styles/resource_card_image_360x300_/public/2019-09/massive-algal-bloom.jpg?itok=pqgXB2yc)
Eutrophication: Why you should care about pond scum
STEM Explained
When fertilizers from agriculture get into lakes and rivers, big problems can result for aquatic ecosystems, food chains & webs!
![Will Booth | General Manager, Regional Hose & Hydraulics Will Booth | General Manager, Regional Hose & Hydraulics](/sites/default/files/styles/career_image/public/6750_13.jpg?itok=EzIFUjeF)
Will Booth
Career Profiles
General Manager
![Shane Monaghan | Product Line Manager Shane Monaghan | Responsable de ligne de produits](/sites/default/files/styles/career_image/public/6749_13.jpg?itok=SM6SQwMH)
Shane Monaghan
Career Profiles
Product Line Manager
![TREVOR ROOTE | MECHANICAL MAINTAINER TREVOR ROOTE | MECHANICAL MAINTAINER](/sites/default/files/styles/career_image/public/trevor_2.jpg?itok=PFx7W6EY)
Trevor Roote (Video)
Career Profiles
Mechanical Maintainer
![Murray Clayton | Forensic Anthropologist Murray Clayton | Forensic Anthropologist](/sites/default/files/styles/career_image/public/6501_13.jpg?itok=k5oCIgLJ)
Murray Clayton
Career Profiles
Forensic Anthropologist & Outreach Coordinator
![Andrew Newman | Mechanical Tree Harvester Andrew Newman | Mechanical Tree Harvester](/sites/default/files/styles/career_image/public/6215_13.jpg?itok=oLEDX3iw)
Andrew Newman (Video)
Career Profiles
Mechanical Tree Harvester
![Kona Williams | Forensic Pathologist Kona Williams | Pathologiste judiciaire](/sites/default/files/styles/career_image/public/6047_13.jpg?itok=ysNCQ19n)
Kona Williams
Career Profiles
Forensic Pathologist
![Katharine Scotton | Environmental Consultant, PGL Environmental Consultants Katharine Scotton | Experte-conseil en environnement, PGL Environmental Consultants](/sites/default/files/styles/career_image/public/6027_13.jpg?itok=QOKoX2Pf)
Katharine Scotton
Career Profiles
Environmental Consultant
![Meredith Ann Epp | Communications and Marketing Manager, Marine Stewardship Council Oceania Meredith Ann Epp | Gestionnaire des communications et du marketing](/sites/default/files/styles/career_image/public/5880_13.jpg?itok=Xrl3oIql)
Meredith Ann Epp
Career Profiles
Communications and Marketing Manager