All of the stars we see at night with our unaided eyes are within
A) 10,000 light-years, which is a small portion of our galaxy.
B) 100,000 light-years, which encompasses most all of our galaxy.
C) 5 million light-years, which encompasses our local group.
D) 14 billion light-years, which encompasses the observable universe.
Question 2
The observable universe is
A) the minor portion of the universe we can observe.
B) the part of the universe that is within the visible electromagnetic spectrum.
C) part of the universe visible to the unaided eye.
D) about 100 billion light years across.
Distribution of glaciers in North America (a) in the late twentieth century, and (b) 18,000 years ag
Much of the dark space between stars, as seen in the sky of the image above, is due to the human eye
School age (late childhood): 6–12 years, or to puberty.
Climate change occurs over millions of years
Why do mosquito bites itch more at night?
When I Look In Your Eyes I Go Crazy