Sunrising

and
Sunsetting
Prediction
-By Group-7

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 ❖ Explanation of what is Sunrise and Sunset.
❖ Sunrise and Sunset occurring time.

Things going ❖ Behind the reasons of these occurrence.

to cover in ❖ Colors during Sunrise and Sunset.
this
presentation ❖ Formulae for predicting Sun rising and setting
time.
❖ Sunrise and Sunset in other planets.

❖ Optical illusions and other phenomena.

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❖ Sunrise refers to the moment when the upper edge of the Sun appears above the
horizon in the morning, marking the beginning of daylight.[1]
❖ It is a natural phenomenon that occurs daily as the Earth rotates on its axis, causing the
Sun to become visible from the vantage point of a specific location on the planet.
❖ Astronomically, sunrise occurs for only an instant: the moment at which the upper limb
of the Sun appears tangent to the horizon.

Sunrise
Picture-1: Sunrise [2] 3
 The term sunrise commonly refers to periods of time both before and after this point:

➢ Twilight, the period in the morning during which the sky is brightening, but the Sun is
not yet visible. The beginning of morning twilight is called astronomical dawn.[3]
➢ The period after the Sun rises during which striking colors and atmospheric effects are
still seen. Civil twilight being the brightest, while astronomical twilight being the
darkest.

Sunrise Picture-2: Twilight [4]

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Civil Twilight : Nautical Twilight: Astronomical Twilight:
Civil twilight is the time Nautical twilight is Astronomical twilight is
when the geometric defined as when the defined as when the
center of the Sun is geometric center of the geometric center of the
between the horizon and Sun is between 12° and Sun is between 18° and
6° below the horizon. 6° below the horizon. 12° below the horizon.

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Pic.-03:Morning Twilight[5] Pic.-04:Evening Twilight[6]
 ❖ Sunset (or sundown) is the disappearance of the Sun below the horizon of
the Earth (or any other astronomical object in the Solar System) due to
its rotation.[7]
❖ The time of actual sunset is defined in astronomy as two minutes before the upper
limb of the Sun disappears below the horizon.
❖ The equinox Sun sets due west at the moment of both the spring and autumn
equinoxes.
❖ As viewed from the Northern Hemisphere, the Sun sets to the northwest (or not at
all) in the spring and summer, and to the southwest in the autumn and winter;
these seasons are reversed for the Southern Hemisphere.

Sunset
Picture-5: Sunset [8] 6
 Colors
❖ At sunrise and sunset, when the path through the atmosphere is longer, the blue and green
components are removed almost completely, leaving the longer-wavelength orange and
red hues seen at those times. The remaining reddened sunlight can then be scattered by
cloud droplets and other relatively large particles to light up the horizon red and orange.

Picture-6: Sunlight travels through atmosphere[9] 7

 Varying colors of sunset
❖ The sun emits a spectrum of rays ranging from high-frequency gamma rays to low-
frequency radio waves. A part of this radiation called the visible spectrum can be
detected by our eyes. This visible spectrum, which we generally call ‘white light,’ is
further composed of seven different wavelengths that we all know by the name
VIBGYOR (or the rainbow colors).

❖ Now, these rays emitted by sun

reach different planets with
different intensities. This is
because, other than the sunlight
itself, the colors that our eyes
see also depend on the medium
(particles) through which it
passes.
Picture-7: Electromagnetic Spectrum[10] 8
 Varying colors of sunset
❖ So, when sunlight passes through different particles the light can get absorbed,
reflected, or scattered, depending on the nature of the particle. Some particles tend to
scatter more of the longer red wavelengths, whereas others go for the shorter blue
waves. And so the resultant color that we see varies accordingly.

Picture-8: Refraction on Earth [11] 9

 Because the size of particles is very
small in Earth’s atmosphere, as
compared to the wavelength of
light. The tiny particles present in
Earth’s atmosphere scatter the blue
wavelengths through a process
why do called ‘Rayleigh Scattering’, so by
the time the light reaches our eyes,
sunsets on only the red remains.

earth look
red?

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Sunset in Mars:
❖ On Mars, the setting Sun appears about two-thirds the size it does from Earth, due to the
greater distance between Mars and the Sun
❖ The colors are typically hues of blue, but some Martian sunsets last significantly longer
and appear far redder than is typical on Earth.

Sunset Picture-9: Sunset in Mars[12]

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 The Martian atmosphere is
dominated by large-sized dust
particles. These particles cause
something called ‘Mie
Scattering,’ which filters out the
Why are red light from the sun’s rays and
only lets the blue reach our eyes.

mars
sunsets
Blue?

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 Sunrise in other Planets:

Planets Colors
Mercury Black
Venus Yellow, Deep Brown
Earth Yellow, Orange, Red
Mars Red
Jupiter White, Orange, Brown, and Red
Saturn Null
Uranus Null
Neptune Null

Sunrise
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Sunset in other Planets:

Planets Colors
Mercury Black
Venus Blue
Earth Orange/ Red
Mars Blue
Jupiter Red
Saturn Super Orange/ Red
Uranus Pink, Purple
Neptune Deep Orange

Sunset
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 False Sunrise
Occasionally a false sunrise occurs, demonstrating a very particular kind
of parhelion belonging to the optical phenomenon family of halos.

Picture-10: False Sunrise [13]

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Angle with respect to horizon :
❖ The stage of sunrise known as false sunrise actually occurs before the Sun truly reaches the
horizon because Earth's atmosphere refracts the Sun's image. At the horizon, the average
amount of refraction is 34 arcminutes, though this amount varies based on atmospheric
conditions.
❖ Also, unlike most other solar measurements, sunrise occurs when the Sun's upper limb,
rather than its center, appears to cross the horizon. The apparent radius of the Sun at the
horizon is 16 arcminutes.
❖ These two angles combine to define sunrise to occur when the Sun's center is 50 arcminutes
below the horizon, or 90.83° from the zenith.

Picture-11: Effects of Atmospheric

Refraction [14]
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Things to know before calculating Sunrise and Sunset time:

1.Location: The sunrise and sunset times depend on your location on the Earth's surface,
primarily in terms of latitude and longitude.

2.Date: The position of the Earth in its orbit around the Sun changes the sunrise and sunset times
throughout the year. Therefore, you need to specify the date for which you want to calculate these
times.

3.Time Zone: The time zone of the location also affects the calculation, as sunrise and sunset
times are usually given in local time.

4.Solar Geometry: Sunrise and sunset occur when the top edge of the Sun's disk is just visible
above the horizon. This involves understanding the geometry of the Earth, Sun, and horizon.

5.Atmospheric Refraction: The bending of light by the Earth's atmosphere causes the Sun to
appear higher in the sky than it actually is, especially near sunrise and sunset. This phenomenon
affects the calculated times.

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First, the highest elevation angle of any location, 𝛼, on any given day of the
year can be calculated as follows:
𝜶 = 𝟗𝟎 ± 𝝋 − 𝜹
Where,
𝜶 = indicates maximum value of the elevation angle .
𝝋 = latitude of the point of interest, which is positive in the northern part of the hemisphere
and negative in the southern part of the hemisphere.
𝜹= the SDA which changes depending on the day number of the year

Second, the hour angle, 𝜽, the most important parameter has to be calculated.

−𝟏
𝐬𝐢𝐧(𝜶) − 𝐬𝐢𝐧( 𝜹) 𝐬𝐢𝐧( 𝝋)
𝜽 = 𝐜𝐨𝐬 [ ]
𝐜𝐨𝐬(𝜹) 𝐜𝐨𝐬( 𝝋)
Third, the EOT(equation of time) has to be calculated.
𝟒𝝅𝒅 𝟐𝝅𝒅
𝑬𝑶𝑻 = 𝟗. 𝟖𝟕𝟑 × 𝐬𝐢𝐧 + 𝟑. 𝟓𝟖𝟖 − 𝟕. 𝟔𝟓𝟓 × 𝐬𝐢𝐧( )
𝟑𝟕𝟓 𝟑𝟔𝟓

Where, 𝒅 = number of day in a year 18

Fourth, the Zuhr time has to be calculated as follows:

𝝀 𝑬𝑶𝑻
𝒁 = 𝟏𝟐: 𝟎𝟎 + 𝑻 − − +𝝉
𝟏𝟓 𝟔𝟎
Where,
𝝀 = Longitude (in degree)
τ = the brief time period that the sun needs to go the zenith point, which is
about 4-5 minutes
𝑻 = Time Zone (e.g. UTC+6)

Fifth, the Sun declination angel, 𝜹, has to be calculated as follows:

𝟐𝝅
𝜹 = −𝟐𝟑. 𝟒𝟓° × 𝐜𝐨𝐬[ × (𝒅 + 𝟏𝟎)]
𝟑𝟔𝟓

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Sunrise and Sunset time Calculation

𝟏 −𝟏
𝒔𝒊𝒏 −𝟎. 𝟖𝟑𝟑° − 𝒔𝒊𝒏(𝜹) 𝒔𝒊𝒏(𝝋)
𝑺𝒖𝒏𝒓𝒊𝒔𝒆 = 𝒁 − × 𝒄𝒐𝒔 [ ]
𝟏𝟓 𝒄𝒐𝒔(𝜹) 𝒄𝒐𝒔(𝝋)

𝟏 −𝟏
𝒔𝒊𝒏 −𝟎. 𝟖𝟑𝟑° − 𝒔𝒊𝒏(𝜹) 𝒔𝒊𝒏(𝝋)
𝑺𝒖𝒏𝒔𝒆𝒕 = 𝒁 + × 𝒄𝒐𝒔 [ ]
𝟏𝟓 𝒄𝒐𝒔(𝜹) 𝒄𝒐𝒔(𝝋)

Where,
𝝋 = Latitude (in degree)

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 Optical illusions and other phenomena
Sometimes just before sunrise or
The Sun appears larger at sunrise after sunset, a green flash can be
than it does while higher in the seen. This is an optical
sky, in a manner similar to phenomenon in which a green spot
the Moon illusion. is visible above the Sun, usually for
no more than a second or two.

Picture-11: Sunrise Illusion(Large) [14] Picture-12: Green Flash during Sunset [15] 21
Let’s watch a video!

22
 [1] https://en.wikipedia.org/wiki/Sunrise
[2] https://en.wikipedia.org/wiki/Sunrise#/media/File:Sunrise_at_Marengo,_Apollo_Bay,_Victoria,_Australia.jpg
[3] https://en.wikipedia.org/wiki/Twilight
[4] https://en.wikipedia.org/wiki/Twilight#/media/File:Twilight_description_full_day.svg
[5] https://en.wikipedia.org/wiki/Twilight#/media/File:Twilight-dawn_subcategories.svg
[6] https://en.wikipedia.org/wiki/Twilight#/media/File:Twilight_subcategories.svg
[7] https://en.wikipedia.org/wiki/Sunset
[8] https://www.linkedin.com/posts/randy-fry-b7a560185_thoughts-on-humility-activity-
7162456122380013568-3gA2
[9] https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.quora.com%2FWhy-does-light-travelling-
from-the-sun-go-through-more-atmosphere-and-why-does-that-make-the-sky-display-different-colors-at-
sunset&psig=AOvVaw1sUL1XX3idAl1yM6nSZPD1&ust=1713723112160000&source=images&cd=vfe&opi=89978
449&ved=0CBIQjRxqFwoTCLD4q6Gy0YUDFQAAAAAdAAAAABAd
[10] https://www.youtube.com/watch?app=desktop&v=FrfcjNTapCU

Bibliography 23
 [11] https://htschool.hindustantimes.com/editorsdesk/knowledge-vine/sunsets-on-mars-are-blue-why-is-it-so
[12] https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.quora.com%2FDo-sunrays-refract-as-they-
enter-the-Earths-atmosphere-When-sunrays-reflect-off-the-surface-do-they-refract-as-they-exit-the-Earths-
atmosphere&psig=AOvVaw1sUL1XX3idAl1yM6nSZPD1&ust=1713723112160000&source=images&cd=vfe&opi=8
9978449&ved=0CBIQjRxqFwoTCLD4q6Gy0YUDFQAAAAAdAAAAABAj
[13] https://en.wikipedia.org/wiki/Sunrise#/media/File:Sunrise-Sunset_angle.svg
[14] https://qph.cf2.quoracdn.net/main-qimg-d16d605f2ac2eb6ece133b7371d83c09-lq
[15] https://encrypted-
tbn0.gstatic.com/images?q=tbn:ANd9GcQT40xeYW1ZYbZN_MwSIcjtJBWopsp0sL7sjow07oo7QQ&s
[16] https://en.wikipedia.org/wiki/Sunrise#/media/File:False_Sunrise.jpg
[17] https://www.vecteezy.com/free-videos/sunrise
[18] https://gml.noaa.gov/grad/solcalc/solareqns.PDF
[19] https://en.wikipedia.org/wiki/Sunrise_equation

Bibliography 24
 Behind this Presentation

Abida Akter Rahad Hossain Loknath Saha Sumaya Sultana Purnima Rani
(2012321107) (2010921117) (2010221137) (2012421147) (2012221177)

Ashrafur Rahman Sraboni Khatun Parvez Hossain Zinnatun Nur Mukta

(2010921187) (2012321217) (2011121227) (1912121227)
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Thanks!

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Share us your inner
thoughts ☺
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