Are you a fan of the Earth? Would you like to see the day and night cycle in action on your Windows Phone lock screen? If the answer to both questions is "affirmative", then you'll be sure to check out Earth Lock Screen. The newly released app does exactly as the name suggests - a dynamically rendered photo of the Earth is displayed on the lock screen as a background.

We say dynamically rendered as the Earth will change to reveal which section of the planet is experiencing daylight and which is currently partying late at night. It's an interesting concept and users can select which region they wish to have focus. The images are rendered and updated offline every two hours, which saves on data and helps reduce the impact on the battery.

You can download Earth Lock Screen from the Windows Phone Store (Windows Phone 8 only) for free. To remove the watermark, purchase the app for $0.99.