Naked Eye Planet Observation in the Solar System

What are Naked Eye Planets – Brief

When we say Naked eye planets ,it means the five brightest planets  known since ancient times , Mercury ,Venus ,Mars ,Jupiter and Saturn. These planets are easily visible in the sky and they are visible to the naked eye. Since ancient astronomers observed that certain celestial objects moved in the night sky relative to fixed stars ,they named them as ‘Asteres Planetai’ meaning wandering stars. These planets look like bright spot of light in the sky.

Important things to Note before Planet Observation

Distinguish between planet and star

  • By its brightness -Planets are brighter than stars and their brightness has regular cyclic variation over a period of time. Stars produce their own light and they are comparatively far away from earth, therefore their light appears to twinkle due to Atmospheric turbulence of earth. On the other hand planets do not produce light rather they reflects the light of Sun. The amount of light a planet reflects also known as albedo depends on the planet’s size and the amount of cloud cover it has. Planet’s brightness depend upon its apparent size ,and its distance from sun
  • By its size– Stars appear like a point or tiny spot in the sky whereas if you closes look at the planet it look like a disk, rather than a tiny spot  since planet are closer to Earth.
  • By its position-Planet position changes slightly relative to the stars from one night to the next. Their position are not fixed on the celestial sphere

Find the Planet’s apparition period:

The period of time during which any given planet (or any other celestial body) can be seen is known as an apparition 

  • Mercury: It is the nearest planet to Sun hence it is visible near the Sun. Mercury is quite difficult to observe due to Sun’s glare ,best time to observe – September and December
  • Venus :This planet can be observed just before sunrise and sunset
  • Mars: Early morning sky and it moves eastward.
  • Jupiter: Pre-dawn skies are the best time to see Jupiter. Jupiter is always located very far away from the sun.
  • Saturn: Evening or morning twilight sky.

Planet rise and set time :

Planet rise and set time is an important factor to note before observation, otherwise there is no sense in observing them.

To know the planet rise and set time you can use this site

http://www.astronomy.com/

Other sites you can use

http://www.almanac.com/astronomy/rise/IL/New%20Delhi/2016-03-04

Location for Planet Search oon website

Enter the location where you need observe the planet, year, month and date

Right location for observation and looking at right part of the sky; 

 Right location for the observation means:
  • A place where there is clear sky and no clouds
  • Minimal lighting from the nearby areas like streets or buildings or houses.
  • A transparent sky without clouds so that light does not get absorbed.
  • Stable air ,no wind to avoid blurring

Right part of the sky: It is very important to know where to see the planets .they best way to locate them is, when they appear as part of constellation, for this you can use a planisphere

If we know the rise or set time of the planets, you can use the planisphere to locate the planets. The idea is simple. First, the planets are always near the ecliptic because the inclinations of the orbital planes of the planets are only a few degrees from the ecliptic

Planets Inclination of Planets Orbits from Ecliptic (Degree)
Mercury 7.00
Venus 3.39
Mars 1.85
Jupiter 1.30
Saturn 2.49

Set the planisphere at the rise or set time of the planets. Figure shows how the planet rises on the east horizon is in Virgo (Vir) and the planet set on the west horizon is in Pisces (Psc).  Two intersecting points in the figure is the place where you can locate the planet by knowing the rise and set time of the planet

The ecliptic, running through the twelve constellations of the zodiac and represented by dotted line, intersects with the horizon at two points

Venus

Image courtesy: https://www.ied.edu.hk/apfslt/v14_issue1/kwokpw/page3.htm#three

Some planisphere do come with Planet finder chart

To find the planet ,follow the steps below to get the location of the naked eye planet.

  • Read the planisphere carefully and acquaint yourself with the ecliptic and the azimuth angles.
  • Turn the planisphere and check the azimuth angle for the planet you want to locate. The values given in the table are the azimuth angles. For example :Search Jupiter , in the table then the year  2016 and then the month- March   for which the azimuth angle  is 171
  • Locate the azimuth and stretch a string or line from the Center which is the Pole star to that angle
  • Now find the particular constellation always a zodiac, the ecliptic runs through the zodiac constellations. The planets must appear near the ecliptic plane, the bright non twinkling star looking like celestial object would be the planet.

Planisphere 1 Planisphere 2

OBSERVATION VIEW OF PLANET

MERCURY 

Through the telescope mercury looks white in colour but it has slight pinkish hue since its angular height above the horizon is low. Due to atmospheric dispersion of light ,the same way sun looks red at sunrise and sun set ,mercury gets this pinkish hue touch .Since mercury is the nearest planet to the sun it moves swiftly hence its brightness varies rapidly at given apparition

Mercury Oservation Image Courtesy http://www.shoestringastronomy.com

VENUS

Venus can be easily viewed and it shines with a brilliant white light. This planet has morning and evening appearance, therefore it is known as Morning and evening star.

Venus

When observe through a telescope Venus has slight bluish color at the edges and it also shows phases like our moon. The best time to observe Venus is when it appears as Morning star, it remains in the sky for longer period

MARS

Mars is known as Red planet and its redness is because of the iron oxide on the surface.This planet rarely appear as Red when observe through telescope ,color varies  from pale orange-yellow to orange-red, depending upon its distance.

Mars from Telescope View

It appears salmon pink in color through the telescope. Mars has two moons Phobos and Deimos which is generally not visible through telescope until and unless you have a large telescope.

JUPITER

Like Venus Jupiter can also appears as bright white in colour in the night sky it always shines brighter than the brightest star in the night sky  that is Sirius .

Jupiter shows small white disk and if carefully observed you can see the Great Red Spot ,North and South Equatorial Belts, also its four Galilean- Ganymede(magnitude +4.6 at opposition), Io (+5.0), Europa (+5.3) and Callisto (+5.6) – can also be seen  through large telescope.

Naked Eye Planet Observation in the Solar System

SATURN

Saturn looks pale yellow to the naked eye.Through telescope you can see Saturn’s ring , it has slight bluish tinch .Saturn is also a brightest object in the sky ,it outshines all the stars in the night sky except Sirius and Canopus

Image credit http://www.johnmiranda.com/telescope.htm