Compare and contrast spiral and elliptical galaxies. (Make at least 2 comparisons.)
How are Earth and Venus similar? How is Venus different from Earth? (Provide two similarities and two differences.)
To compare and contrast spiral and elliptical galaxies, we need to understand their characteristics and features. Here are two comparisons between spiral and elliptical galaxies:
1. Structure: Spiral galaxies have a distinct structure of flat, rotating disks with rotating arms spiraling outwards from a central bulge. On the other hand, elliptical galaxies lack this spiral structure and instead appear as smooth, elongated spheroids without any well-defined disks or arms.
2. Stellar Populations: Spiral galaxies typically have a mix of younger and older stars, often indicating ongoing star formation activity. They also contain interstellar gas and dust, which provides the fuel for star formation. In contrast, elliptical galaxies consist mainly of older stars. Their star formation activity has mostly ceased, and their interstellar gas content is significantly lower compared to spiral galaxies.
Now let's move on to the similarities and differences between Earth and Venus:
Similarities:
1. Terrestrial Planets: Both Earth and Venus are classified as terrestrial planets, meaning they have solid, rocky surfaces like the inner planets of our solar system.
2. Similar Sizes: Earth and Venus have comparable sizes, with Venus being only slightly smaller than Earth. In fact, they are often referred to as sister planets due to their similar size.
Differences:
1. Atmosphere: Earth's atmosphere primarily consists of nitrogen (78%) and oxygen (21%), which is critical for supporting life as we know it. In contrast, Venus has a thick, toxic atmosphere composed mainly of carbon dioxide (96%) with traces of nitrogen and sulfur. Its atmosphere creates a runaway greenhouse effect, resulting in extreme temperatures and pressures on the planet's surface.
2. Surface Conditions: Earth possesses a diverse range of environments, including oceans, continents, and various ecosystems that support an abundance of life. In contrast, Venus has a hostile surface environment with an average temperature of around 900 degrees Fahrenheit (475 degrees Celsius) and atmospheric pressure around 92 times greater than Earth's. Venus is also characterized by a barren and desolate landscape, lacking water and exhibiting a dense cloud cover that obscures its surface.
To summarize, while Earth and Venus share certain characteristics, such as terrestrial planet status and comparable sizes, their atmospheres, surface conditions, and potential for supporting life differ significantly.
Hot, very hot, like 800 deg F
Atmosphere is not air (N2 and O2) but CO2
day about 100 earth days long
similar size
similar year (about 60% earth)