The Scientific MethodThe Scientific Method

The Scientific MethodThe Scientific Method

7 steps of the scientific method7 steps of the scientific method1. 1. 2. 2. 3. 3. 4. 4. 5. 5. 6. 6. 7. Report you findings7. Report you findings

ObservationObservation

May be the most important step. May be the most important step.

Before you can really do anything, you must first Before you can really do anything, you must first notice that something needs to be done.notice that something needs to be done.

Observation is really recognizing a discrepancy. Observation is really recognizing a discrepancy.

Astronomers who relied on their powers of Astronomers who relied on their powers of Observation:Observation:

Galileo, Newton, Ptolemy Galileo, Newton, Ptolemy

Statement of the problemStatement of the problem

Always written as a “ ” question.Always written as a “ ” question. What is the effect of increased temperature on cricket What is the effect of increased temperature on cricket

chirps?chirps? What is the effect of increased speed on fuel What is the effect of increased speed on fuel

consumption?consumption?Stating the observed discrepancy in the manner of Stating the observed discrepancy in the manner of

a question allows one to develop an answer.a question allows one to develop an answer.What questions lead to a cause and effect. “Why” What questions lead to a cause and effect. “Why”

questions can be answered with a simple questions can be answered with a simple “because”.“because”.

hypothesishypothesis

Defined as an __________________Defined as an __________________The hypothesis is what you think is the best The hypothesis is what you think is the best

answer to the question you posed when you answer to the question you posed when you stated the problem.stated the problem.

Best when written as a cause and effect.Best when written as a cause and effect.When developing a hypothesis, always keep in When developing a hypothesis, always keep in

mind the original observation, and the problem mind the original observation, and the problem that you are trying to answer.that you are trying to answer.

Designing an experimentDesigning an experiment

ExperimentExperiment- is - is which which addresses a particular problem.addresses a particular problem.

What are some things to think about when What are some things to think about when designing an Experiment?designing an Experiment?

Things to think about when Things to think about when designing an experimentdesigning an experiment

Materials that are readily availableMaterials that are readily available

Parts of an experimentParts of an experiment ControlControl: Aspect of the experiment that is held : Aspect of the experiment that is held

constant so as to have a standard of constant so as to have a standard of comparison.comparison.

__________________________________: the factor that is adjusted : the factor that is adjusted by the experimenter.by the experimenter.

: The factor which changes : The factor which changes as a result of the independent variableas a result of the independent variable

The dependent variable depends on The dependent variable depends on the independent variablethe independent variable

Experiment (continued)Experiment (continued) : part of the experiment : part of the experiment

that is used as a control.that is used as a control.ConstantConstant: :

: group with in the : group with in the experiment which all things are the same experiment which all things are the same as the control group except for one aspect, as the control group except for one aspect, which is referred to as the _________.which is referred to as the _________.

Collect and analyze dataCollect and analyze data

After the experiment has been conducted, After the experiment has been conducted, data must be collected and analyzed.data must be collected and analyzed.

Things to think about:Things to think about:

Draw ConclusionsDraw Conclusions

Conclusions are judgments based on an Conclusions are judgments based on an experience and the interpretation of data.experience and the interpretation of data.

Conclusions can be different.Conclusions can be different.

We all have different experienceWe all have different experience

Some conclusions are better than others. Some conclusions are better than others.

The difference between a good astronomer and The difference between a good astronomer and an average astronomer may be the ability to an average astronomer may be the ability to draw relevant conclusions.draw relevant conclusions.

Report findingsReport findings

In the field of Astronomical research this entails In the field of Astronomical research this entails writing paperswriting papers

Basically you are responsible for informing the Basically you are responsible for informing the community of your resultscommunity of your results

You recognized a gap in our knowledge about You recognized a gap in our knowledge about the world around us. Once you know the the world around us. Once you know the information you need to tell the public so as to fill information you need to tell the public so as to fill the gap.the gap.

That means being able to properly communicate That means being able to properly communicate

The cyclical nature of scienceThe cyclical nature of science

If your hypothesis is not proven correct by If your hypothesis is not proven correct by your experiment you must reject it, and your experiment you must reject it, and draw whatever conclusions that you can draw whatever conclusions that you can then develop a new hypothesis and then develop a new hypothesis and experiment. experiment.

TheoryTheory

When conclusions associated with a When conclusions associated with a specific hypothesis are continuously specific hypothesis are continuously supported by many different experiments supported by many different experiments then the hypothesis is considered a then the hypothesis is considered a theorytheory

When a theory is continually support and When a theory is continually support and considered to be a rule of nature then it is considered to be a rule of nature then it is said to be a said to be a lawlaw. .

The Nature of ScienceThe Nature of Science

Types of reasonTypes of reason : reasoning from a particular set of : reasoning from a particular set of

facts to a general rule.facts to a general rule. : suggesting something is true about : suggesting something is true about

a specific case from a known general rule.a specific case from a known general rule.

Types of Types of researchresearch

: controlled experiments that result : controlled experiments that result in counts or measures. Numerical datain counts or measures. Numerical data

: observational data often : observational data often descriptions of observations of animal behaviordescriptions of observations of animal behavior..

Science and SocietyScience and Society Society must take responsibility for how a scientific Society must take responsibility for how a scientific

discovery is used.discovery is used. But science is limited to addressing questions that can But science is limited to addressing questions that can

be answered using the scientific method, and the be answered using the scientific method, and the methods MUST be ethical.methods MUST be ethical.

A scientist does NOT decide what is ethical and what is A scientist does NOT decide what is ethical and what is not, rather society dictates the ethical guidelines that a not, rather society dictates the ethical guidelines that a scientist must adhere to.scientist must adhere to.

EthicsEthics- is a study of the standards of right and wrong.- is a study of the standards of right and wrong. TechnologyTechnology- The application of scientific research to - The application of scientific research to

society’s needs and problems.society’s needs and problems.

Metric SystemMetric System

International system of International system of measurementsmeasurements

In 1975 the United States passed the In 1975 the United States passed the Metric Conversion Act. The intent was for Metric Conversion Act. The intent was for the U.S. to use the metric system like the the U.S. to use the metric system like the rest of the world. What happened instead rest of the world. What happened instead was that metric units were placed on was that metric units were placed on labels in addition to the standard unitslabels in addition to the standard units

We will use metric units in this classWe will use metric units in this class

PrefixesPrefixes

PrefixPrefix SymbolSymbol x factorx factorKiloKilo k k 10001000DeciDeci d d 0.10.1CentiCenti c c 0.010.01MilliMilli m m 0.0010.001MicroMicro 0.0000010.000001NanoNano n n 0.0000000010.000000001

Units of MeasureUnits of Measure

LengthLengthMeter (m)Meter (m)1 meter = 100 centimeters (cm)1 meter = 100 centimeters (cm)10mm=1cm=0.1dm=0.01m=0.00001km10mm=1cm=0.1dm=0.01m=0.00001km

ExamplesExamples 7 m = 700 cm = 7000 mm7 m = 700 cm = 7000 mm 7 m = 0.007 km7 m = 0.007 km 92 m = 0.092 km92 m = 0.092 km 550 cm = 5.50 m550 cm = 5.50 m 3.6 m = 3600 mm3.6 m = 3600 mm

Units of MeasureUnits of Measure Notice there were no units for EXTREMELY large distances.Notice there were no units for EXTREMELY large distances. In astronomy there are SEVERAL units of measure for great In astronomy there are SEVERAL units of measure for great

distances:distances: Astronomical UnitAstronomical Unit (AU) – The average distance between the (AU) – The average distance between the

Earth and the Sun.Earth and the Sun. 1 AU = 1.5 x 101 AU = 1.5 x 101010 m or 150 million km m or 150 million km

Mercury = 0.4 AU from the Sun Mercury = 0.4 AU from the Sun Earth = 1AU from the SunEarth = 1AU from the Sun Pluto = 40 AU from the SunPluto = 40 AU from the Sun

Light yearLight year - (NOT A UNIT OF TIME!) The distance that light - (NOT A UNIT OF TIME!) The distance that light travels in a year.travels in a year. Light travels 9.46 x 10Light travels 9.46 x 101515 m in on year m in on year

ParsecParsec – Distance at which an observer sees the maximum – Distance at which an observer sees the maximum angle between the Sun and the Earth to be one arc second. angle between the Sun and the Earth to be one arc second. (We may discuss this later, we most likely will not be using parsecs as a unit of (We may discuss this later, we most likely will not be using parsecs as a unit of measure.)measure.) 1 parsec = 3.26 light years (3.09 x 101 parsec = 3.26 light years (3.09 x 101313 km). km).

Units of MeasureUnits of Measure

MassMassThe amount of matter in an objectThe amount of matter in an objectWe will work mainly in gramsWe will work mainly in grams

1000 grams (g) = 1 Kilogram (kg)1000 grams (g) = 1 Kilogram (kg)1 gram = 1000 milligrams (mg)1 gram = 1000 milligrams (mg)ExamplesExamples

4.601 kg = 4601 g4.601 kg = 4601 g 9 g = 9000 mg9 g = 9000 mg

Units of MeasureUnits of Measure Volume: the amount of space an object Volume: the amount of space an object

occupies.occupies. SI (SI (System InternationalSystem International) for volume is the liter (L)) for volume is the liter (L) 1000L = 1 kiloliters (kL)1000L = 1 kiloliters (kL) We will mostly be using milliliters (ml)We will mostly be using milliliters (ml)

1000 mL = 1 L1000 mL = 1 L

The great thing about SI (The great thing about SI (System InternationalSystem International) is ) is that 1 mL = 1cmthat 1 mL = 1cm33

Volume can be easily converted to mL or L from Volume can be easily converted to mL or L from the measurement of lengththe measurement of length

MeniscusMeniscus – the curved surface of a liquid. – the curved surface of a liquid.

Units of MeasureUnits of Measure

Density= mass/volumeDensity= mass/volumeUsed to identify an objectUsed to identify an objectD = M/VD = M/VUnits is g/ml or g/cmUnits is g/ml or g/cm33 How many grams is a substance if it has a How many grams is a substance if it has a

density of 19.3 and a volume of 3.6 ml?density of 19.3 and a volume of 3.6 ml?

Answer = 69 gAnswer = 69 g

Units of MeasureUnits of Measure Time and TemperatureTime and Temperature

Time is measured in secondsTime is measured in seconds

Temperature is actually a measure of the kinetic Temperature is actually a measure of the kinetic energy of a substance (how quickly the energy of a substance (how quickly the molecules that make up a substance are molecules that make up a substance are moving)moving)

Temperature is measured in Kelvin or CelsiusTemperature is measured in Kelvin or Celsius We will use CelsiusWe will use Celsius Water freezes at 0Water freezes at 0ooC and boils at 100C and boils at 100ooCC Body temp is about 37Body temp is about 37ooCC

Kelvin (K)Kelvin (K)

Kelvin (K) is mostly used in Chemistry and PhysicsKelvin (K) is mostly used in Chemistry and Physics O K is called O K is called absolute zeroabsolute zero.. Absolute zeroAbsolute zero is when molecular motions stops. It is when molecular motions stops. It

is impossible to get anything colder than absolute is impossible to get anything colder than absolute zero. That means that there are no negative zero. That means that there are no negative temperatures in Kelvin.temperatures in Kelvin.

To convert between Celsius (C) and Kelvin (K):To convert between Celsius (C) and Kelvin (K): C + 273 = KC + 273 = K K – 273 = CK – 273 = C

Water boils at 373 K and freezes at 273 KWater boils at 373 K and freezes at 273 K

Odds and EndsOdds and Ends

Accuracy: how close your value is to the Accuracy: how close your value is to the actual value- this gets better with practice.actual value- this gets better with practice.

Accuracy depends on UAccuracy depends on U

Precision: indicated by the number of Precision: indicated by the number of significant digits and depends on the significant digits and depends on the quality of the measuring instrument.quality of the measuring instrument.

Significant digits are the numbers off the Significant digits are the numbers off the measuring device. measuring device.

The BasicsThe Basics PlanetPlanet – A large body in orbit around a star. Must be mostly – A large body in orbit around a star. Must be mostly and and

have a have a path. path. Planets in our solar system (9): Mercury, Venus, Earth, Mars, Jupiter, Saturn, Planets in our solar system (9): Mercury, Venus, Earth, Mars, Jupiter, Saturn,

Uranus, Neptune, (Pluto). Uranus, Neptune, (Pluto). – – A body orbiting a planet.A body orbiting a planet.

Examples: Our moon, Ganymede, Io, Europa.Examples: Our moon, Ganymede, Io, Europa. Solar SystemSolar System – The Sun, planets, their moons and other bodies that orbit – The Sun, planets, their moons and other bodies that orbit

the Sun. the Sun. Our Sun is a star.Our Sun is a star. – – A massive, gaseous body held together by gravity and A massive, gaseous body held together by gravity and

generally emitting light. generally emitting light. Normal stars generate energy by nuclear reactions in their interiors. Normal stars generate energy by nuclear reactions in their interiors.

– – The path in space followed by a celestial body.The path in space followed by a celestial body. ALL celestial bodies rise in the East and set in the West. A result of the ALL celestial bodies rise in the East and set in the West. A result of the

rotation of the Earth.rotation of the Earth. – – The drift of a planet westward against the The drift of a planet westward against the

background of stars. background of stars. Normally planets shift eastward because of orbital motion. Normally planets shift eastward because of orbital motion. The planet does NOT actually reverse its motion. The change in direction is The planet does NOT actually reverse its motion. The change in direction is

caused by the change in position from which we view the planet as the Earth caused by the change in position from which we view the planet as the Earth overtakes and passes it.overtakes and passes it.

Solstice versus equinoxSolstice versus equinox - the path traced by the sun as it crosses - the path traced by the sun as it crosses

the celestial sphere.the celestial sphere. Solstice (winter and summer)Solstice (winter and summer) – The beginning of winter and – The beginning of winter and

summer. The solstice occurs when the sun is at its greatest summer. The solstice occurs when the sun is at its greatest distance north (in June) or south (in December) of the distance north (in June) or south (in December) of the celestial equator.celestial equator. Summer solstice – Near June 21Summer solstice – Near June 21 Winter solstice – Near December 21 Winter solstice – Near December 21

– – The time of the year when the number of The time of the year when the number of hours of daylight and night are approximately equal. The hours of daylight and night are approximately equal. The spring and fall (vernal and autumnal) equinoxes mark the spring and fall (vernal and autumnal) equinoxes mark the beginning of spring and fall seasons.beginning of spring and fall seasons. Spring (vernal) equinox – March 21 - start of springSpring (vernal) equinox – March 21 - start of spring Fall (autumnal) equinox – Near September 21 - start of autumnFall (autumnal) equinox – Near September 21 - start of autumn

EclipsesEclipses

One will occur in Sept. - Visible in S. Am.One will occur in Sept. - Visible in S. Am.Occurs when the moon happens to lie Occurs when the moon happens to lie

exactly between the Earth and Sun, or exactly between the Earth and Sun, or when the Earth lies exactly between the when the Earth lies exactly between the Sun and Moon. Sun and Moon.

All three bodies will be in a straight lineAll three bodies will be in a straight lineThere are two types of EclipsesThere are two types of Eclipses

Lunar EclipseLunar EclipseSolar Eclipse Solar Eclipse

EclipsesEclipses

Lunar EclipseLunar Eclipse – Occurs when the Earth – Occurs when the Earth passes between the Sun and the Moon, passes between the Sun and the Moon, casting its shadow on the moon. (Fig 1.15)casting its shadow on the moon. (Fig 1.15)

Solar EclipseSolar Eclipse – Occurs when the Moon – Occurs when the Moon passes between the Sun and the Earth, passes between the Sun and the Earth, blocking our view of the Sun. (Fig 1.14)blocking our view of the Sun. (Fig 1.14)

EllipseEllipse

Do not confuse an ellipse with an eclipse.Do not confuse an ellipse with an eclipse.An An ELLIPSEELLIPSE is a geometric shape, similar is a geometric shape, similar

to a circle, but elongated in one direction.to a circle, but elongated in one direction.The path of the Earth’s orbit around the The path of the Earth’s orbit around the

Sun is in the shape of an Sun is in the shape of an ellipseellipse..

Historical AstronomersHistorical Astronomers

PtolemyPtolemy Herschel, WilliamHerschel, William CopernicusCopernicus LaPlace, Pierre-SimonLaPlace, Pierre-Simon Tycho BraheTycho Brahe Halley, EdmundHalley, Edmund Johannes KeplerJohannes Kepler Cassini, GiovaniCassini, Giovani Galileo GalileiGalileo Galilei Hipparchus of NicaeaHipparchus of Nicaea NewtonNewton HertzsprungHertzsprung DopplerDoppler HubbleHubble