• 31 Environmental sciences
• 17 Astronomy
• 17 Space exploration
• 16 Airplanes
• 9 Renewable energy sources
• 8 Design and construction
• 8 Space vehicles
• 7 Exploration
• 6 Architecture
• 6 Conservation and restoration
• 5 Biology
• 5 Planets
• 5 Research aircraft
• 4 Automobiles
• 3 Aerospace engineering
• 3 Bridges
• 3 Computer science
• 3 Environmental protection
• 3 International Space Station
• 3 Solar energy
• 3 Speed records
• 3 Telescopes
• 3 Transport planes
• 3 Wildlife conservation
• 2 Aeronautical sports

• 250 English

• 6 Great Britain
• 4 Australia
• 4 India
• 4 Mars (Planet)
• 3 Antarctica
• 3 Egypt
• 2 Barcelona (Spain)
• 2 China
• 2 Himalaya Mountains
• 2 Italy
• 2 Netherlands
• 2 Sun
• 2 Sydney Harbour (N.S.W.)
• 2 United States
• 2 Venus (Planet)
• 1 Abū Ẓaby (United Arab Emirates)
• 1 Africa
• 1 Alaska
• 1 Alexandria
• 1 Alexandria (Egypt)
• 1 Arctic region
• 1 Arctic regions
• 1 Asia
• 1 Aspen (Colo.)
• 1 Barcelona

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