Cosmic Origins & Evidence
This standard unit measures the distance light travels in one Earth year and is used to gauge huge gaps between stars and galaxies.
What is a light-year?
Along the horizontal axis of an H-R diagram, surface temperature decreases toward this side, placing red stars on the far end.
What is the right side?
Because of its massive gravitational pressure and core temperature, a Blue Giant burns through its nuclear fuel much faster than a Yellow Dwarf, resulting in a much shorter lifespan.
What is a lifespan (or life cycle)
In a study testing how different amounts of fertilizer affect tomato plant growth, the amount of fertilizer applied represents this variable.
What is the independent variable?
To find the mass of a mineral sample in grams without using digital equipment, a student adjusts the 100g, 10g, and 1g sliders on this laboratory tool.
What is a triple beam balance?
When light from distant galaxies is stretched to longer wavelengths as they move away, it shifts toward this end of the electromagnetic spectrum, proving the universe is expanding.
What is redshift?
Coolest stars appear Red, while the hottest stars on the H-R diagram appear this color.
What is Blue?
To an observer on Earth, our Sun (a yellow dwarf) appears significantly brighter than distant blue giants like Rigel primarily because of this property.
What is proximity to Earth (distance)?
A student writes, "If a potted plant receives 8 hours of sunlight daily, then it will grow taller than a plant receiving 4 hours." This statement is an example of a testable prediction.
What is a hypothesis?
A block of oak wood has a mass of 120g and occupies a volume of 200mc3 Calculating its mass divided by its volume yields this physical property (0.6g/cm3), what are you finding?
What is density?
During the first few minutes following the Big Bang, nuclear reactions synthesized these two lightest elements in abundance across the early cosmos.
What are Hydrogen and Helium?
About 90% of all stars, including stable stars actively fusing hydrogen in their cores, reside in a prominent diagonal band across the H-R diagram known by this name.
What is the Main Sequence?
Unlike Yellow Dwarfs, which only fuse lighter elements, massive Blue Giants reach core temperatures hot enough to fuse heavy elements up to this metal prior to collapsing.
What is Iron?
Plate Tectonic Theory is supported by extensive evidence, whereas an initial guess about why a volcano erupts is merely this.
What is a hypothesis (versus a scientific theory)?
Oceanographers notice that cold, highly saline water sinks beneath warm, fresh water at estuaries because salt adds mass without significantly increasing volume, thereby doing this to the water's density.
What is increasing density?
This fundamental attractive force pulled together hot, dense areas of gas in the expanding early universe to jump-start star formation.
What is gravity?
Located in the upper-right region of the H-R diagram, stars in this phase are extremely bright/luminous despite having relatively cool surface temperatures.
What are Red Giants (or Red Supergiants)?
When a low-to-medium mass Yellow Dwarf like our Sun exhausts its core hydrogen fuel, it expands into this next evolutionary stage.
What is a Red Giant?
To ensure that only the effect of light intensity is measured on algae growth, a researcher keeps water temperature, pH, and nutrient levels identical across all samples—a setup known as this.
What is a controlled experiment?
When air near the Earth's surface is heated by the sun, its particles spread apart, making the warm air less dense and causing it to do this relative to the surrounding cool air.
What is rise?
This faint thermal background radiation, uniformly detected in all directions of deep space, serves as major evidence of the hot, dense initial expansion of the universe.
What is Cosmic Microwave Background (CMB)?
If Star A and Star B have the same surface temperature, but Star A is located higher up on the vertical axis, Star A must have a much greater value for this physical property.
What is size / radius (or Luminosity)?
While a Yellow Dwarf eventually sheds its outer layers and leaves behind a White Dwarf, a massive Blue Giant ends its life cycle in a catastrophic explosion called this
What is a Supernova?
Based on a data table showing that average global ocean surface temperatures have increased over the past century, a scientist asserts that marine heatwaves are becoming more frequent.
What is a scientific claim (or conclusion)?
A giant cargo ship made of heavy steel stays afloat in ocean water because the fluid exerts an upward force equal to the weight of the displaced water.
What is buoyant force (or buoyancy)?