Astronomy 3 Chapter 1 Homework

Could we see a galaxy that is 50 billion light-years away?

No, because it would be beyond the bounds of our observable universe.

On the cosmic calendar, which compresses the history of the universe into a single year, about when did life arise on Earth?

September; Earth formed in early September on the cosmic calendar. Life apparently arose on Earth within less than a billion years after that, which means it was still in September (because each month on the cosmic calendar represents about 1.2 billion years).

When we say the universe is expanding, we mean that:

The average distance between galaxies is growing with time.

The star Betelgeuse is about 600 light-years away. If it explodes tonight:

we won't know about it until 600 years from now

Distance in 1 light year?

9.5*10^12 or 9.5 trillion kilometers

According to current scientific estimates, when did the Big Bang occur?

About 14 billions years ago

On the cosmic calendar, which compresses the history of the universe into a single year, about when did Earth form?

Early September; The cosmic calendar compresses the 14-billion-year history of the universe into 1 year, which means that each month represents about 1.2 billion years. The solar system's age of 4 ½ billion years therefore puts its birth in early September.

What is our "cosmic address" from small to large?

Earth, solar system, Milky Way Galaxy, Local Group, Local Supercluster, universe

On the cosmic calendar, which compresses the history of the universe into a single year, about when did early humans first walk on Earth?

Just a few hours before midnight on December 31. The cosmic calendar compresses the 14-billion-year history of the universe into 1 year, which means that each day represents about 1/365 of 14 billion years, or about 40 million years. Early humans arose just a few million years ago, which therefore means just a few hours before the present moment (the stroke of midnight on December 31) on the cosmic calendar.

The fact that nearly all galaxies are moving away from us, with more distant ones moving faster, helped us to conclude that:

The universe is expanding

If stars existed but galaxies did not A) we would probably still exist anyway B) we would not exist because life on Earth depends on the light of galaxies C) we would not exist because we are made of material that was recycled in galaxies

We would not exist because we are made of material that required recycling in galaxies.

The age of our solar system is about how old compared to the age of the universe?

one-third of the age of the universe.

What is an astronomical unit?

the average distance from Earth to the Sun-about 150 million km or 93,000,000 miles

The total number of stars in the observable universe is roughly equivalent to what landscape on Earth?

the number of grains of sand on all the beaches on Earth

If we represent the solar system on a scale that allows us to walk from the Sun to Pluto in a few minutes, then:

the planets would all be marble size or smaller and the nearest stars would be thousands of miles away.