OBSERVING THE NIGHT SKY

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OBSERVING THE NIGHT SKY

• 2. The Use Of Star Charts Observing The Stars,
  Planets And Meteors

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What We Will Learn

• How to use Star Charts to locate objects
• Observing stars and constellations
• Observing the Moon and Planets
• Observing Meteors and Meteor Showers

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Preparing to look at the sky

• Say you decide to look at the sky some night.
• Avoid moonlit nights, which are bad for star
• gazing.
• During the day or evening have a look at the
  appropriate Star Chart and familiarize yourself
  with what you are likely to see.
• Note the important stars and constellations and
  note where they are located in relation to one
  another. Note important pointers.

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More preparation

• Locate a field, a terrace or roof somewhat
  protected from electric lights from which the
  sky will be visible.
• At the location chosen clearly identify and
  remember the North and East directions.
• Keep a small torch ready and cover its
• front portion with some red paper or
• cellophane.

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The Star Chart

• The Star Chart shows the position of stars and
  constellations.
• NOTE East is marked to the left, not right!
• Used held overhead with North pointing North and
  East to true East. Practice this.

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Star Charts

• A given set of Star Charts will normally be
  designed for a given time at a given latitude.
• At other latitudes objects will be found
  either to the North or South of the indicated
  location. At other times one will have to look
  West or East.
• The Charts given here are for around 9pm at a
  latitude of around 15N. However, they can with
  a little care be used anywhere in India.

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Naked eye observations

• Around 9pm or later go to the spot chosen, get
  comfortable and get your eyes used to the
  darkness. If necessary close your eyes for some
  time.
• Keep the Star Chart overhead with its North
  pointing North and its East pointing East. Use
  the dim red light of the torch to see the Chart.

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Using the Chart, try to locate some bright
stars and patterns. Once you are sure you
have identified an object or portion of the
sky, use this as a pointer to other objects
in the Chart. If you have difficulties,
check that you are looking at the correct part
of the sky for that time of the night.
Remember the Earth is rotating!
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An example . Say we wished to observe the
night sky at about 9pm around 15 January. We
first go to the Guide Chart and find that we
should use Chart 2 for the stars that are
overhead at 9pm ..
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Guide Chart
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Now we go to Chart 2 .. and find from it that
the bright constellation Orion should be a
little south-east of overhead. Orion is very
useful because it is eye catching and can used
as a pointer to other stars and constellations

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Chart 2
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Note that Orion looks like a man wearing a belt,
Betelguese is a red giant while Rigel is a bluish
white giant. Note the Great Nebula M42 in the
Sword of Orion. The Belt of Orion points north
westwards to the red star Aldebaran in the V of
Taurus. Further in the same direction lies the
faint star cluster, the Pleiades (the Seven
Sisters). Further still lies the conch-like
constellation Perseus and its red star Algol.
To the north of Orion lies the pentagon shaped
constellation Auriga.

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.To the South East of Orion lies the
bright constellation Canis Major and Sirius the
brightest star in the heavens. To see this part
of the sky we need to go Chart 3 (see the Guide
Chart). By 12am Gemini will be overhead .
and so on ..
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Chart 3
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Objects not in the Star Charts

• There are cosmic objects which are not shown
• in Star Charts. A list of the important ones
• The Moon.
• The Planets
• Shooting Stars (Meteors) Meteor Showers
• Comets
• Novae and Supernovae
• These objects are not shown because they either
• move with respect to the fixed stars or vary in
• brightness. You should not be confused by them.

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The Moon

• The Moon is a cold, solid object that is seen by
  reflected sunlight.
• Its orbit around Earth is inclined to the
  ecliptic. This is why we see its phases.
• It is a good exercise to make a note of its
  appearance each night over 28 days.
• Its eclipses, a little rare, are worth watching.
• The Moon has craters which may be seen through a
  small telescope or binoculars.

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The Planets

• The Planets are cold objects like the Earth which
  move around our Sun and are seen by reflected
  sunlight.
• In the night sky they appear to move with respect
  to the background stars. Since they lie close to
  the ecliptic, they are found in the Zodiacal
  constellations.
• The inner planets, Mercury Venus, move
  relatively fast over weeks and are found close to
  the Sun. The outer planets appear to move slowly
  over the seasons and years.

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The orbits of the Planets around the Sun
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The Solar System in the Milky Way Galaxy
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Observing the Inner Planets

• Mercury, Venus, Mars, Jupiter Saturn are
  visible to the naked eye. Dont twinkle like the
  stars.
• Mercury is difficult. Can only be seen close to
  the Sun at sunrise or sunset
• Venus, the brightest object in the sky after the
  Sun and Moon. Visible as the Evening Star after
  sunset or as the Morning Star before sunrise. The
  phases of Venus can be seen even with a small
  telescope.

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Outer Planets their Moons

• Mars is clearly reddish in colour. Moves fairly
  fast in its orbit.
• Jupiter is brighter than Sirius but slow moving.
  Four of its many moons, Io, Europa, Ganymede and
  Callisto can be seen through small telescopes.
• Saturn appear yellowish and is slow moving. Its
  beautiful rings require a small telescope for
  viewing.

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Observing Meteors Meteor Showers

• Meteors or Shooting Stars are dust particles or
  rocks that burn up when they enter Earths
  atmosphere.
• Sit comfortably or lie down and look for some
  time, say 15-30mins, at any part of the sky.
  You are likely to see a Meteor.
• Meteor Showers are spectacular bursts of meteors
  that occur at specific times of the year at well
  defined locations in the sky. Try seeing some.
  The table tells you where to look.

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Meteor Showers