Astronomers have developed a new method using “twin stars” to measure stellar distances.
Climbing the Ladder
At the beginning of the 20th century, we were just beginning to map out our galaxy. By the end of the 20th century we had discovered a universe billions of light years across.
Standard Variables
In the late 1800s Henrietta Leavitt was hired by Edward Pickering of the Harvard College Observatory. “Hired” in this case being a loose term, since Leavitt was not initially paid for her work. She was assigned the task of cataloging the brightness of variable stars from photographic plates. This is a tedious process, which is why it was done by women (known as Pickering’s Harem).
Parallax View
How is it possible to say with confidence that one star is 8 light-years away, while another is 640 light-years away? There are actually several methods to determine cosmic distances, and these are combined to create what is known as the cosmic distance ladder, but the oldest and most direct method uses the property of parallax.
Primeval Atom
The origin of the universe is often portrayed in popular science as a vast sea of darkness. Centered in this darkness is a bright point of light, which suddenly expands, filling your view with light, fading into a dance of galaxies. Of course this raises all sorts of questions: What did the universe expand into? What triggered the initial explosion? Where did all that matter and energy come from? The problem is, this isn’t how cosmologists see the big bang at all.
How Astronomy Supports Evolution
If evolution is correct (and it is) then it must have occurred over billions of years, not a mere 10,000 or so. So how do we know — really, really know — that the Universe is billions of years old? It all comes down to a bit of astronomy.
Type Casting
A new supernova was discovered in a nearby galaxy in October of 2012, and it’s recently been identified as a type Ia supernova. Astronomers and astrophysicists are interested in the type of supernova because there are several ways a supernova can occur, and they are categorized by type.
Supernova
The light of a supernova tells us what type it is. One type, known as type Ia, has a standard brightness, and we can use that fact to measure galactic distances.
Cepheid Variables
There are stars known as Cepheid variables that change in brightness over time. The rate at which their brightness varies is proportional to their brightness, which allows us to determine the distance to galaxies millions of light years away.