Putting the Size of the Observable Universe in Perspective. The age of the universe is about 13.75 billion years. The diameter of the observable universe is estimated at about 28 billion parsecs (93 billion light-years). As a reminder, a light-year is a unit of length equal to just under 10 trillion kilometres (or about 6 trillion miles).
Red eye is the result of changes in the blood vessels in your eye that make your eye look red or bloodshot; it may occur in one or both eyes. Red eye is usually caused by irritation, infection or trauma. Even everyday causes, such as coughing, sneezing, crying, and lack of sleep, can lead to redness in your eye. Red eye is often accompanied by other eye symptoms, including burning, itching, soreness, tearing and discharge.
When these glands don't function properly, known as Meibomian gland dysfunction (MGD), it can result in dry patches on your eyes. These become sore, and extra tears are produced as a reflex. This is the most likely cause of watering eyes. Other causes. Other problems that can cause extra tears to be produced include: the lower eyelid sagging away from the eye â this makes it difficult for tears to reach the drainage ducts ; eyelids that roll inwards inflammation of the edges of the eyelids (blepharitis) blocked or narrowed tear ducts ; eye irritation (for example, from chemical fumes or grit)