Rare, all-red auroras are produced by high-altitude oxygen, at heights of up to 200 miles. Nitrogen produces blue or purplish-red aurora. The connection between the Northern Lights and sunspot activity has been suspected since about 1880.
In developed countries, the average birth weight of a full-term newborn is approximately 3.4 kg (71â2 lb), and is typically in the range of 2.7â4.6 kg (6.0â10.1 lb).
The average length of full-term babies at birth is 20 in. (50 cm), although the normal range is 18 in. (45.7 cm) to 22 in. (60 cm). In the first month, babies typically grow 1.5 in. (4 cm) to 2 in. (5 cm). Your baby's head will grow at its fastest rate during the first 4 months after birth than at any other time. This increase is due to rapid brain growth. The average head circumference at birth is about 13.5 in. (34.5 cm).