Vocabulary Flashcards for ASTR 104: Elementary Astronomy
Question 1: The Earth's Movement
Statement: The Sun revolves around the Earth.
Correct Answer: FALSE
Explanation: The Earth revolves around the Sun in an elliptical orbit.
Question 2: Moons of the Planets
Question: Which planet in the solar system has the most moons, and how many does it currently have?
Correct Answer: Saturn has the most moons, with 146 confirmed moons as of 2025.
Question 3: Sizes of Stars
Statement: All stars are the same size.
Correct Answer: FALSE
Explanation: Stars come in various sizes; some are much larger or smaller than our Sun.
Question 4: Black Holes
Statement: A black hole is a 'hole' in space.
Correct Answer: FALSE
Explanation: A black hole is a region in space where gravity is extremely strong, causing anything, including light, to be unable to escape.
Question 5: Meteor Visibility
Statement: Meteors are only seen at night.
Correct Answer: FALSE
Explanation: While some meteors are more visible at night, meteor showers can occur during the day as well.
Chapter 1: Science and the Universe: A Brief Tour
Section 1.1: The Nature of Astronomy
Definition: Astronomy is defined as the study of the objects that lie beyond our planet Earth and the processes by which these objects interact with one another.
Involvement of History: Astronomy indeed involves history because understanding the universe includes knowledge of its evolution over time.
Ongoing Development: Astronomy is not a 'dead science'; it is rapidly evolving as new types of data are gathered and interpreted by scientists.
Section 1.2: The Nature of Science
Correct Answer: Science is not merely a body of knowledge, but a method by which we attempt to understand nature and how it behaves.
Scientific Method Steps:
This method begins with many observations over a period of time.
Propose a hypothesis—a preliminary idea or model to explain observations.
The hypothesis must be a proposed explanation that can be tested.
Modify the hypothesis as needed based on further evidence and observations.
Section 1.3: Laws of Nature
Scientific Laws Definition: Scientific laws are the “rules” that govern how natural systems behave.
Universality of Scientific Laws: Yes, these rules are the same everywhere in the universe, allowing us to apply known laws to understand phenomena in distant star systems and galaxies.
Section 1.4: Numbers in Astronomy
Distance to the Sun: Approximately 150,000,000 kilometers.
Scientific Notation: How to express this in scientific notation:
1 AU = 1.5×10^11 m = 1.5×10^8 km (Astronomical Unit).
Additional Notes on Measurements
Light-Year: Is a unit of distance; it defines the distance light travels in one year.
Speed of Light: Light travels at 300,000 kilometers per second (constant).
Distance Light Travels in One Year: A light-year equals approximately 9.46×10^12 kilometers.
Section 1.5: Consequences of Light Travel Time
**Impact on Astronomy: **
Light Travel Time and Distance: The farther we observe in space, the longer the light has traveled to reach us, meaning we are looking further back in time.
Historical Observations: Observing distant objects means seeing them as they were when the light left, not as they are today.
Cosmic Time Capsule: Light travel time acts as a time delay, enabling astronomers to study the universe's past and evolution.
Finite Speed of Light: Light does not reach us instantly; key light travel times are:
Moon: ~1 second
Sun: ~8 minutes
Nearest Star: ~4 years
Across Our Galaxy: ~90,000 years
Nearest Galaxies: ~2 million years
Farthest Galaxies: ~billions of years.
Section 1.6: A Tour of the Universe
Section 1.7: The Universe on the Large Scale
Objects observable from Earth include:
Stars
ISS and Satellites
The Moon
Lunar Eclipses
The Sun
Eclipse Types:
Partial Solar Eclipse
Annular Solar Eclipse
Total Solar Eclipse
Zodiac Light
Auroras
Categories of Celestial Objects
Terrestrial Planets
Gas Giants
Dwarf Planets
Constellations Observed
Leo
Sagittarius
Aries
Gemini
Virgo
Capricornus
Libra
Scorpius
Cancer
Pisces
Aquarius
Other Celestial Phenomena
Meteors
Meteor Showers
Comets
Asteroids
The Milky Way
Magellanic Clouds
Star Clusters
Globular Clusters
Nebulae
Stellar Nurseries
Planetary Nebulae
Supernovae
Supernova Remnants
Exoplanets Detection
Notable Galaxies:
Andromeda
M51
Black Holes:
Supermassive Black Hole in the center of Messier 87 and its shadow
Galactic Structures:
Galaxy Clusters
Galaxy Superclusters
Cosmic Phenomena
Gravitational Lensing
Cosmic Background Radiation
Universe Timeline
Age of the Universe: The universe's age is vast, making it challenging to comprehend its timeline compared to humanity's brief existence. To visualize this, consider compressing the entire history of the Universe since the Big Bang into a single year; this perspective illustrates humanity’s short appearance on the cosmic timeline.
The Essence of Astronomy
Astronomy is the science that studies the entire Universe, requiring knowledge from various sciences, including Physics, Chemistry, Geology, and Biology.
The core of Science is to find the best explanation of observed phenomena.
A Theory is an explanation that is subject to revision if observations reveal it to be incorrect. An essential element of any theory is that it should allow predictions that can be tested.
Scientific Notation in Astronomy
Purpose: It is useful for expressing very large and very small numbers in a way that is easier to write and perform calculations on.
Speed of Light: Constant at 300,000 km/s.
Light-Year: A useful unit of measure for distances outside of our Solar System.
Visibility of Celestial Objects: On a clear, dark night, the unaided eye can see up to five planets, the Moon, several thousand stars, and the occasional meteor or comet. Light from distant objects has been traveling towards us for billions of years, allowing us to observe the Universe's history.