sÀÆ

CAvÀgÀ gÁ¶ÖçÃAiÀÄ RUÉÆüÀ «eÁÕ£À ªÀµÀð-2009
INTERNATIONAL YEAR OF ASTRONOMY - 2009
mÉÆæÃd£ï PÀÄëzÀæ UÀæºÀUÀ¼ÀÄ
Trojan Asteroids
AiÀiÁªÀÅzÉà JgÀqÀÄ PÁAiÀÄUÀ¼À £ÀqÀÄªÉ PÉ®ªÀÅ
©AzÀ Ä UÀ ¼ À ° è JgÀ q À Æ PÁAiÀ Ä UÀ ¼ À
UÀ Ä gÀ Ä vÁé P À µ À ð t ±À Q Û MAzÀ P É Æ Ì A zÀ Ä
«gÀÄzÀÞªÁV ¥Àæ¨sÁªÀªÉà E®èzÁUÀÄvÀÛzÉ.
EzÀ£ÀÄß ªÉÆzÀ®Ä eÉ. ¯ÉUÁæAeï (1736-1830)
JA§ UÀtÂvÀdÕ vÉÆÃj¹PÉÆlÖzÀÝjAzÀ F
©AzÀÄUÀ½UÉ ¯ÉUÁæAeï ©AzÀÄUÀ¼ÀÄ JAzÀÄ
ºÉ¸ÀgÀÄ. F ªÀiÁzÀjAiÀÄ°è UÀÄgÀÄ UÀæºÀzÀ
¯ÉUÁæAeï ©AzÀÄUÀ¼À£ÀÄß vÉÆÃj¸À¯ÁVzÉ. F
©AzÀÄUÀ¼À°ègÀĪÀ ¸ÀtÚ PÁAiÀÄUÀ¼ÀÄ UÀÄgÀÄ
UÀæºÀzÀ PÀPÉëAiÀįÉèà ¸ÀÆAiÀÄð£À£ÀÄß ¸ÀÄvÀÄÛvÀÛªÉ.
UÀÄgÀÄ UÀæºÀ¢AzÀ 60 rVæUÀ¼ÀµÀÄÖ »AzÉ
CxÀªÁ ªÀÄÄAzÉ EgÀÄvÀÛªÉ. EªÀÅUÀ½UÉ
mÉÆæÃd£ï JAzÀÄ ºÉ¸ÀgÀÄ.
The gravitational forces due to two
massive bodies cancel out at some
specific points. These points are
called Lagrangian points after the
mathematician J Lagrange (17361830) who first calculated them
mathematically. A low mass body
placed at any of these Lagrangian
points will maintain its relative
position from the two massive
bodies. For the Sun and Jupiter
some asteroids are located at two of
the Lagrangian points. These are
Trojan Asteroids.
In this model, we show the orbit of
Jupiter and the location of
Lagrangian points exactly 60
degrees on either side of Jupiter.
Trojan asteroids
(leading group)
Lagrangian
point L4
Jupiter
UÀÄgÀÄ
Sun
Lagrangian
point L3
mÉÆæÃd£ï
PÀëÄzÀæUÀæºÀUÀ¼ÀÄ
«µÀĪÀzï ©AzÀÄUÀ¼À CAiÀÄ£À
Precession of equinoxes
¨sÀÆ«ÄAiÀÄ ¨sÀæªÀÄuÉ ªÀÄvÀÄÛ ¥Àj¨sÀæªÀÄuÉUÀ¼À£ÀÄß £ÁªÀÅ
zÉÊ£ÀA¢£À ºÁUÀÆ ªÁ¶ðPÀ ZÀ®£É JAzÀÄ
UÀÄgÀÄw¸ÀÄvÉÛêÉ. PÀ¼ÉzÀ ¸ÀºÀ¸ÁægÀÄ ªÀµÀðUÀ¼À
CzsÀåAiÀÄ£À¢AzÀ F CPÀëªÀÅ ¤zsÁ£ÀªÁV
N¯ÁqÀÄwÛzÉ JA§ CA±À ¨É¼ÀQUÉ §A¢zÉ. EzÀ£ÀÄß
¨sÀÆ«ÄAiÀÄ ªÀÄÆgÀ£ÉAiÀÄ ZÀ®£É J£ÀߧºÀÄzÀÄ.
EzÀ g À PÁgÀ t GvÀ Û g ÁAiÀ Ä t ªÀ Ä vÀ Ä Û
zÀ Q ë u ÁAiÀ Ä £À U À ¼ À ° è ºÁUÀ Æ «µÀ Ä ªÀ U À ¼ À ° è
¸ÀÆAiÀÄð£À ¸ÁÜ£À ¤zsÁ£ÀªÁV §zÀ¯ÁUÀÄwÛzÉ.
GzÁºÀgÀuÉUÉ 2000 ªÀµÀðUÀ¼À »AzÉ ªÉÄõÀ
gÁ²AiÀÄ°è «µÀĪÀ GAmÁUÀÄwÛvÀÄÛ. FUÀ «ÄãÀ
gÁ²AiÀÄ°è DUÀÄwÛzÉ. ªÀÄPÀgÀ¸ÀAPÁæAw ªÀÄvÀÄÛ
GvÀÛgÁAiÀÄtUÀ½UÉ ªÀåvÁå¸À EgÀĪÀÅzÀPÀÆÌ EzÉÃ
PÁgÀt. EzÀÄ §ºÀ¼À ¤zsÁ£ÀªÁzÀ ZÀ®£É ¸ÀĪÀiÁgÀÄ
26,000 ªÀµÀðUÀ¼ÀÄ. ¨sÀÆ«ÄAiÀÄ DªÀvÀð£ÀzÀ
CPÀëzÀ ¢QÌ£À°è PÁtĪÀ £ÀPÀëvÀæPÉÌ £ÁªÀÅ zsÀÄæªÀ
J£ÀÄßvÉÛÃªÉ EA¢UÉ 16000 ªÀµÀðUÀ¼À £ÀAvÀgÀ
ªÉ à UÁ CxÀ ª Á C©ü f vï JA§ £À P À ë v À æ
zsÀÄæªÀªÁUÀÄvÀÛzÉ.
The Earth rotates about its axis as it
revolves around the Sun. The effect of
these motions are apparent on a daily
or annual basis. However, the Earth has
a third motion in which the tip of the
rotation axis describes a full circle in
26,000 years. Due to this motion, the
change in the position of the Sun at
solstices and equinoxes become
noticeable in a few centuries. Thus the
vernal equinox which was occurring
when the Sun was in Aries two
thousand years ago, now occurs when
the Sun is in Pisces. This is also the
reason for the difference in the
celebration of Makara Sankranthi and
Uttarayana.
One other consequence of this motion
is that 16000 years from now the axis of
rotation of the Earth will point at a
different star called Vega. Then that will
be our Pole star.
ZÀAzÀæ£À ¨sÀæªÀÄuÉ ªÀÄvÀÄÛ ¥Àj¨sÀæªÀÄuÉ
Rotation and Revolution of Moon
ZÀAzÀæ ¨sÀÆ«ÄAiÀÄ£ÀÄß ¸ÀÄvÀÄÛªÀ PÀPÉëAiÀÄzÉÆAzÀÄ
ªÉ Ê ²µÀ Ö ö å«zÉ . CzÀ g À ¨s À æ ª À Ä uÉ ªÀ Ä vÀ Ä Û
¥Àj¨sÀæªÀÄuÉAiÀÄ CªÀ¢ü MAzÉÃ. ¸ÀĪÀiÁgÀÄ 27.32
¢£ÀUÀ½UÉƪÉÄä ¨sÀÆ«ÄAiÀÄ£ÀÄß ¸ÀÄvÀÄÛªÀ ZÀAzÀæ
CzÉà CªÀ¢üAiÀÄ°è vÀ£Àß CPÀëzÀ ªÉÄÃ¯É MAzÀÄ
¨sÀæªÀÄuÉAiÀÄ£ÀÆß ªÀÄÄV¸ÀÄvÀÛzÉ. F vÀvÀéªÀ£ÀÄß F
ªÀiÁzÀj¬ÄAzÀ «ªÀj¸À¯ÁVzÉ. F ªÉʲµÀÖöåzÀ
¥ÀjuÁªÀĪÁV ¨sÀƫĬÄAzÀ £ÉÆÃqÀĪÀ
£ÀªÀÄUÉ ZÀAzÀæ£À MAzÉà ¨sÁUÀ AiÀiÁªÁUÀ®Æ
PÁtÄvÀÛzÉ. F ªÀiÁzÀjAiÀÄ°è F ¨sÁUÀªÀ£ÀÄß
©½AiÀÄ §tÚ¢AzÀ UÀÄgÀÄw¸À¯ÁVzÉ.
The Moon rotates about its axis
and revolves around the Earth.
The rotation period of the Moon
and the period of revolution
around Earth are both equal to
27.32 days. (For the Earth these
periods are 1 day and 365 days
respectively). As a consequence,
from the Earth, the same
hemisphere of the Moon is
visible.
E£ÉÆßAzÀÄ CA±ÀªÀ£ÀÆß £ÁªÀÅ UÀªÀĤ¸À§ºÀÄzÀÄ.
ZÀ A zÀ æ £ À ªÉ Ä Ã¯É ¤AvÀ Ä ¨s À Æ «ÄAiÀ Ä £À Ä ß
£ÉÆÃrzÁUÀ, DPÁ±À¢AzÀ MAzÉà ¨sÁUÀzÀ°è
¨sÀÆ«Ä ¹ÜgÀªÁV EgÀĪÀAvÉ PÁtÄvÀÛzÉ.
¨sÀÆ«ÄUÉ AiÀiÁªÁUÀ®Æ «ªÀÄÄRªÁVgÀĪÀ
ZÀAzÀæ£À MAzÀÄ ¤¢ðµÀÖ ¨sÁUÀzÀ°è ¤AvÀÄ
£ÉÆÃqÀĪÀªÀjUÉ ¨sÀÆ«Ä PÁtĪÀÅzÀÄ ¸ÁzsÀåªÉÃ
E®è.
This model here shows this as
the white half. The Black half can
never be seen from the Earth.
¨sÀÆ DªÀvÀð£ÀzÀ CPÀë ªÀÄvÀÄÛ zsÀÄæªÀ £ÀPÀëvÀæ
Rotation of the Earth and the Pole Star
¸ÀÆAiÀÄð ¥ÀǪÀðzÀ°è GzÀ¬Ä¹ ¥À²ÑªÀÄzÀ°è
PÀAvÀĪÀÅzÀÄ. EzÉà jÃw ZÀAzÀæ, UÀæºÀ, £ÀPÀëvÀæ
ªÀ Ä ÄAvÁzÀ J®è DPÁ±À P ÁAiÀ Ä UÀ ¼ À Æ
¥À Ç ªÀ ð zÀ ° è GzÀ ¬ Ĺ ¥À ² Ñ ª À Ä zÀ ° è
PÀAvÀĪÀŪÀÅ. 24 UÀAmÉUÀ¼À ¨sÀÆ DªÀvÀð£ÀªÉÃ
EzÀPÉÌ PÁgÀt. £ÁªÀÅ F ZÀ®£ÉAiÀÄ£ÀÄß
UÀ滸À¯ÁgɪÀÅ. DzÀgÉ DPÁ±ÀPÁAiÀÄUÀ¼À
ZÀ®£É UÉÆÃZÀgÀªÁUÀÄvÀÛzÉ. bÀwæAiÀÄ£ÀÄß
wgÀÄV¹zÀ ºÁUÉ JAzÀÄ G¥ÀªÉÄAiÀÄ£ÀÄß
PÉÆqÀ§ºÀÄzÀÄ. bÀwæAiÀÄ ªÀÄzsÀåzÀ ©AzÀÄ
wgÀÄUÀĪÀÅ¢®è JAzÀÄ ºÉÃUÉ C¤ß¸ÀĪÀÅzÉÆÃ
ºÁUÉAiÉÄà ¨sÀÆ CPÀëzÀ ªÉÄðgÀĪÀ £ÀPÀëvÀæªÀÇ
wgÀÄUÀĪÀÅ¢®è. CzÉà zsÀÄæªÀ £ÀPÀëvÀæ. CzÀÄ
GzÀ¬Ä¸ÀĪÀÅzÀÆ E®è. PÀAvÀĪÀÅzÀÆ E®è.
We see that the Sun rises in the east
and sets in the west. Similarly all the
celestial objects also rise in the east
and set in the west. This is because of
the rotation of the Earth from west to
east once in 24 hours. We are not
able to perceive the rotation of the
Earth, instead feel that all the stars go
around in the opposite direction.
However, stars along the axis of
Earth's rotation itself will neither rise
nor set, just as the dot on the central
handle of a rotating umbrella does
not participate in the rotation of the
umbrella. The model demonstrates
this idea. The star along the axis
which appears stationary is the Pole
Star.
ZÀAzÀæ£À PÀ¯ÉUÀ¼ÀÄ
Phases of Moon
ZÀAzÀæ ¨sÀÆ«ÄAiÀÄ£ÀÄß ¸ÀÄvÀÄÛvÀÛzÉ. »ÃUÉ ¸ÀÄwÛ
§gÀĪÁUÀ CzÀgÀ ¥ÀæPÁ²vÀ ¨sÁUÀzÀ ¨ÉÃgÉ ¨ÉÃgÉ
¨sÁUÁA±ÀUÀ¼ÀÄ £ÀªÀÄUÉ PÁtÄvÀÛªÉ. DzÀÝjAzÀ MªÉÄä
UÀÄAqÀUÉ, MªÉÄä CzsÀð MªÉÄä UÉgÉAiÀÄAvÉ
PÁtÄvÀÛzÉ. ¸ÀÆAiÀÄð ªÀÄvÀÄÛ ZÀAzÀæ JgÀqÀÆ MAzÉÃ
¢QÌ £ À ° è z ÁÝ U À ¥À æ P Á²vÀ ¨s Á UÀ £À ª À Ä UÉ
«ªÀÄÄRªÁVgÀÄvÀÛzÉ. DUÀ £ÀªÀÄUÉ ZÀAzÀæ
PÁtĪÀÅ¢®è. PÉ®ªÀÅ ¢£ÀUÀ¼À £ÀAvÀgÀ ¥ÀæPÁ²vÀ
¨sÁUÀzÀ MAzÀA±À ªÀiÁvÀæ PÁtÄvÀÛzÉ. EzÀÄ ¨Á®
ZÀAzÀæ CxÀªÁ gÉÃSÁ ZÀAzÀæ. K¼ÀÄ¢£ÀUÀ¼À £ÀAvÀgÀ
CzsÀð ZÀAzÀæ PÁtÄvÀÛzÉ. EzÀÄ ZÁAzÀæªÀiÁ¸ÀzÀ
ªÉÆzÀ® ¥ÁzÀ. ºÀÄtÂÚªÉÄAiÀÄ ¢£À ZÀAzÀæ ªÀÄvÀÄÛ
¸ÀÆAiÀÄðgÀ £ÀqÀÄªÉ ¨sÀÆ«Ä EgÀĪÀÅzÀjAzÀ
¥ÀæPÁ²vÀ ¨sÁUÀ ¥ÀÇwð PÁtÄvÀÛzÉ. CzÁzÀ K¼ÀÄ
¢£ÀUÀ½UÉ ¥ÀÅ£ÀB CzsÀð ZÀAzÀæ PÁtÄvÀÛzÉ. EzÀÄ
ZÁAzÀæ ªÀiÁ¸ÀzÀ PÉÆ£ÉAiÀÄ ¥ÁzÀ.
We know that the Moon goes around the
Earth. One half of it is always illuminated
by the Sun. However, we see different
fractions of the illuminated part of the
Moon as it completes one revolution.
These are the phases of the Moon. When
the Sun and the Moon are in the same
direction, the Sunlit half is away from us;
hence we cannot see the Moon. On that
day the Moon and the Sun rise and set
together. This is called the New Moon.
After a couple of days, as the Moon moves
away from the direction of the Sun we see
a small fraction. This phase is called the
crescent. Gradually we see more and
more of the illuminated half. When they
are on the opposite sides of the Earth, the
Moon rises as the Sun sets. This is Full
Moon. In the model a ring has been placed
around the Moon to indicate the half that is
visible to us. Notice that before the Full
Moon one half of the illuminated half Moon
is visible to us; this is called First Quarter.
After the Full Moon the other half of the
illuminated half is visible to us. This is
called the Last Quarter.
¥Àæw wAUÀ¼ÀÆ UÀæºÀtUÀ¼ÉÃPÁUÀĪÀÅ¢®è?
Why there are no Eclipses Every Month
ZÀAzÀæ£À £ÉgÀ¼ÀÄ ¨sÀÆ«ÄAiÀÄ ªÉÄÃ¯É ©zÁÝUÀ
¸ÀÆAiÀÄðUÀæºÀtªÁUÀÄvÀÛzÉ. ¨sÀÆ«ÄAiÀÄ £ÉgÀ½£À
ªÀÄÆ®PÀ ZÀAzÀæ ºÁzÀÄ ºÉÆÃUÀĪÀÅzÀ£ÀÄß
ZÀAzÀæUÀæºÀt J£ÀÄßvÉÛêÉ. ZÀAzÀæ ¨sÀÆ«ÄAiÀÄ£ÀÄß
¸ÀÄvÀÄÛªÀ PÀPÉë PÁæAwªÀÈvÀÛPÉÌ CAzÉæ ¨sÀƫĸÀÆAiÀÄð EgÀĪÀ ¸ÀªÀÄvÀ®PÉÌ NgÉAiÀiÁVzÉ. F
PÁgÀt¢AzÀ ¥Àæw CªÀiÁªÁ¸ÉåAiÀÄ°èAiÀÄÆ
¸ÀÆAiÀÄðUÀæºÀt, ¥Àæw ºÀÄtÂÚªÉÄUÀÆ ZÀAzÀæUÀæºÀt
DUÀĪÀÅ¢®è. ¨sÀÆ«ÄAiÀÄ PÀPÉëAiÀÄ vÀ®ªÀ£ÀÄß
ZÀAzÀæ PÀPÉëAiÀÄ vÀ®ªÀÅ bÉâ¸ÀĪÀ ©AzÀÄUÀ½UÉ
¥ÀªÀðUÀ¼ÉAzÀÄ ºÉ¸ÀgÀÄ. gÁºÀÄ ªÀÄvÀÄÛ PÉÃvÀÄ
JAzÀÄ F ©AzÀÄUÀ½UÉ ºÉ¸ÀgÀÄ. ZÀAzÀæ F
©AzÀÄUÀ¼À ¸À«ÄÃ¥À EzÁÝUÀ ºÀÄtÂÚªÉÄ,
CªÀiÁªÁ¸ÉåUÀ¼ÁzÀgÉ ªÀiÁvÀæ UÀæºÀtUÀ¼ÁUÀÄvÀÛzÉ.
The Sun is eclipsed when Moon's
shadow falls on the Earth. A Lunar
eclipse occurs when the Moon
enters the Earth's shadow. For this
to happen the Sun, the Moon and
the Earth have to be in the same
plane, actually in a straight line.
The orbit of the Moon is inclined to
the Earth-Sun plane called the
Ecliptic. Therefore, the shadow of
the Moon will not fall on the Earth
every New Moon day. Similarly the
shadow of the Earth will not fall on
the Moon every Full Moon day.
However, eclipses occur on those
occasions when the Moon is near
the points of intersection of the two
planes namely the orbital plane of
the Moon and the Ecliptic. These
are called Nodes. These nodal
points are known as Rahu and
Ketu.
»ªÀÄÄäR ZÀ®£É
Retrograde Motion
gÁ²ZÀPÀæzÀ £ÀPÀëvÀæUÀ¼À »£É߯ÉAiÀÄ°è UÀæºÀUÀ¼À
ZÀ®£ÉAiÀÄ£ÀÄß UÀÄgÀÄw¸À§ºÀÄzÀÄ. ªÉÄõÀ¢AzÀ
ªÀȵÀ¨sÀ, ªÀȵÀ¨sÀ¢AzÀ «ÄxÀÄ£À »ÃUÉ ¤¢ðµÀÖªÁzÀ
¢QÌ£À°è CªÀÅ ZÀ°¸ÀÄvÀÛªÉ. DzÀgÉ DUÁUÉÎ CªÀÅ
vÁvÁÌ°PÀªÁV F ¢PÀÌ£ÀÄß §zÀ°¹zÀ ºÁUÉ
PÁtÄvÀÛzÉ. GzÁºÀgÀuÉUÉ ªÀȵÀ¨sÀ¢AzÀ ªÉÄõÀ
»ÃUÉ. PÉ®ªÀÅ ¢£ÀUÀ¼À §½PÀ CªÀÅ ªÉÆzÀ°£À
¢QÌ£À¯Éèà ZÀ®£ÉAiÀÄ£ÀÄß ªÀÄÄAzÀĪÀgɸÀÄvÀÛªÉ.
EzÀPÉÌ »ªÀÄÄäR ZÀ®£É JAzÀÄ ºÉ¸ÀgÀÄ. UÀæºÀUÀ¼À
ZÀ®£ÉAiÀÄ ªÉÃUÀzÀ°è ªÀåvÁå¸À«gÀĪÀÅzÀjAzÀ »ÃUÉ
PÁtÄvÀÛzÉ. E°ègÀĪÀ ªÀiÁzÀj F vÀvÀéªÀ£ÀÄß
«ªÀj¸ÀÄvÀÛzÉ. ¨sÀÆ«Ä ªÀÄvÀÄÛ ºÉÆgÀªÀ®AiÀÄzÀ
UÀæºÀªÉÇAzÀÄ ¸ÀÆAiÀÄð£À ¸ÀÄvÀÄÛwÛªÉ. UÀæºÀzÀ
ZÀ®£ÉAiÀÄ ¢PÀÌ£ÀÄß «ªÀj¸À®Ä ¨sÀƫĬÄAzÀ
CzÀPÉÌ MAzÀÄ ¸ÀgÀ¼À£ÀÄß ¸ÉÃj¹, ¢Ã¥ÀzÀ ªÀåªÀ¸ÉÜ
ªÀiÁqÀ¯ÁVzÉ. ¨É¼ÀQ£À ©AzÀÄ«£À ZÀ®£ÉAiÉÄÃ
¨sÀƫĬÄAzÀ PÀAqÀAvÉ UÀæºÀzÀ ZÀ®£É. ¨sÀÆ«Ä F
ºÉÆgÀªÀ®AiÀÄzÀ UÀæºÀªÀ£ÀÄß zÁn ªÀÄÄAzÉ
ºÉÆÃzÁUÀ ¸ÀgÀ½£À ¢PÀÄÌ vÁvÁÌ°PÀªÁV
«gÀÄzÀÞªÁUÀÄvÀÛzÉ. ¨É¼ÀQ£À ©AzÀÄ«£À ZÀ®£É
»ªÀÄÄäRªÁUÀÄvÀÛzÉ. CAzÀgÉ ¨sÀƫĬÄAzÀ
PÀAqÀAvÉ UÀæºÀ »ªÀÄÄäRªÁV ZÀ°¹zÀAvÉ
PÁtÄvÀÛzÉ.
The movement of planets can be
observed against the background of stars
forming the zodiacal constellations. Each
day a planet's position in the sky is
displaced and over a period it moves in a
specific direction - Aries to Taurus, Taurus
to Gemini and so on.
However
occasionally it appears as though it
reverses the direction temporarily, ie., it
appears to move from Taurus to Aries.
This is called retrograde motion.
The
planet in reality does not reverse its
motion. After a few days it reverts to the
original direction. This can be explained
by the relative motion of the planets with
respect to the Earth.
The model
demonstrates this effect. The Earth and
an outer planet are shown moving around
the Sun. To represent the position of the
planet in the sky, a rod is connected to the
two planets with a light source. The spot
of light indicates the position in the sky. As
the Earth overtakes the planet, the spot of
light appears to move in the reverse
direction.
UÀæºÀUÀ¼À£ÀÄß £ÉÆÃqÀĪÀ CªÀPÁ±À
Duration of Visibility of Planets
¨sÀÆ«Ä ªÀÄÆgÀ£ÉAiÀÄ UÀæºÀ. §ÄzsÀ ªÀÄvÀÄÛ ±ÀÄPÀæ F JgÀqÀÄ
UÀæºÀUÀ¼ÀÄ ¨sÀÆ«ÄAiÀÄ PÀPÉëVAvÀ ºÀwÛgÀzÀ PÀPÉëUÀ¼À°è
¸ÀÆAiÀÄð£À£ÀÄß ¸ÀÄvÀÄÛvÀÛzÉ. DzÀÝjAzÀ ¨sÀƫĬÄAzÀ
PÀAqÀAvÉ ¸ÀÆAiÀÄð ªÀÄvÀÄÛ CªÀÅUÀ¼À £ÀqÀÄ«£À PÉÆãÀ
¤¢ðµÀÖ «ÄwAiÉƼÀVgÀÄvÀÛzÉ. DzÀÝjAzÀ F JgÀqÀÄ
UÀæºÀUÀ¼À£ÀÄß ¸ÀAeÉ ¸ÀÆAiÀÄð ªÀÄļÀÄVzÀ ªÉÄÃ¯É ¸Àé®à
ºÉÆvÀÄÛ CxÀªÁ ¸ÀÆAiÉÆÃðzÀAiÀÄPÉÌ ªÀÄÄAZÉ ¸Àé®à ºÉÆvÀÄÛ
ªÀiÁvÀæ £ÉÆÃqÀ®Ä CªÀPÁ±À«zÉ. CªÀÅUÀ¼À PÀPÉëUÀ¼À
ªÁå¸ÀPÀÌ£ÀÄUÀÄtªÁV F CªÀ¢ü ªÀÄvÀÄÛ PÉÆãÀ
ªÀåvÁå¸ÀªÁUÀÄvÀÛzÉ. ¸ÀÆAiÀÄð¤UÉ ¸À«ÄÃ¥ÀªÁVgÀĪÀ
§ÄzsÀ 29 rVæUÀ½VAvÀ PÀrªÉÄ PÉÆãÀzÀ°è PÁtÄvÀÛzÉ.
±ÀÄPÀæUÀæºÀ 47 rVæUÀ¼À PÉÆãÀQÌAvÀ PÀrªÉÄ PÉÆãÀzÀ°è
PÁtÄvÀÛzÉ. DzÀ PÁgÀt §ÄzsÀ UÀæºÀ ¸ÀĪÀiÁgÀÄ JgÀqÀÄ
UÀAmÉUÀ½VAvÀ ºÉZÀÄÑ PÁ® £ÉÆÃqÀ®Ä ¹UÀĪÀÅ¢®è;
±ÀÄPÀæUÀæºÀ ¸ÀĪÀiÁgÀÄ ªÀÄÆgÀÄ UÀAmÉUÀ¼ÀµÀÄÖ ºÉÆvÀÄÛ
£ÉÆÃqÀ®Ä ¹UÀÄvÀÛzÉ.
G½zÀ UÀæºÀUÀ¼ÀÄ ¨sÀÆ«ÄAiÀÄ ºÉÆgÀV£À PÀPÉëUÀ¼À°è
¸ÀAZÀj¸ÀĪÀÅzÀjAzÀ CªÀÅUÀ½UÉ »ÃUÉ PÉÆãÀzÀ «Äw
E®è. DzÀÝjAzÀ gÁwæAiÀÄ AiÀiÁªÀÅzÉà ºÉÆwÛ£À°è
CªÀÅUÀ¼À£ÀÄß £ÉÆÃqÀ®Ä CªÀPÁ±À«zÉ.
The Earth is the third planet from the
Sun. Planets Mercury and Venus are
in orbits smaller than that of the Earth.
Hence the angular separation
between one of them and the Sun as
seen from the Earth is always small.
As a consequence we see them either
just before Sunrise in the morning or in
the evening after Sunset. The smaller
the orbit, the smaller is the angular
separation. Therefore the innermost
planet Mercury is seen at a very small
angle from the Sun; the maximum
angle is about 280 which corresponds
to about two hours. That is, Mercury
cannot be seen for more than two
hours either before Sunrise or after
Sunset. For Venus this angle is 470,
which corresponds to about three
hours.
The other planets in the orbits larger
compared to Earth can be seen at any
angle from the Sun; therefore they can
be visible at any time during the night.
UÀæºÀUÀ¼À ¨s˪ÀiÁåPÁgÀ
Equatorial Bulge of Planets due to Rotation
¨sÀÆ«ÄAiÀÄ DPÁgÀ ¥Àj¥ÀÆtðªÁzÀ UÉÆüÀªÀ®è.
¸ÀªÀĨsÁdPÀ ¥ÀæzÉñÀUÀ¼À°è ªÁå¸À ¸Àé®à ºÉZÀÄÑ
EgÀÄvÀÛzÉ. EzÀPÉÌ ¨s˪ÀÄå DPÁgÀ JAzÀÄ ºÉ¸ÀgÀÄ.
EzÀPÉÌ PÁgÀt vÀ£Àß CPÀëzÀ ªÉÄÃ¯É ¸ÀÄvÀÄÛªÀ ¨sÀæªÀÄuÉ.
J®è DPÁ±ÀPÁAiÀÄUÀ½UÀÆ F jÃwAiÀÄ ¨sÀæªÀÄuÉ
EzÉÝà EgÀÄvÀÛzÉ. DzÀgÉ F ¨sÀæªÀÄtzÀ ªÉÃUÀ
ºÉZÁÑzÁUÀ UÀæºÀ ¨s˪ÀiÁåPÁgÀ ¥ÀqÉAiÀÄÄvÀÛzÉ.
EzÀ£ÀÄß F ªÀiÁzÀjAiÀÄ°è vÉÆÃj¸À¯ÁVzÉ.
CPÀëzÀ ªÉÄÃ¯É ¸ÀÄvÀÄÛªÀ vɼÀĪÁzÀ vÀUÀr£À ºÁ¼É
ªÀÈvÁÛPÁgÀzÀ°ègÀÄvÀÛzÉ. ¨sÀæªÀÄt ªÉÃUÀ ºÉaÑzÀAvÉ
¸ÀªÀĨsÁdPÀ ªÀÈvÀÛzÀ ¨sÁUÀ «¸ÀÛj¸ÀÄvÀÛzÉ. EzÀ£ÀÄß
¥À j ÃQë ¸ À ® Ä C£À Ä PÀ Æ ®ªÁUÀ Ä ªÀ A vÉ ¸À t Ú
UÀÄgÀÄvÀÄUÀ¼À£ÀÄß ªÀiÁqÀ¯ÁVzÉ.
UÀæºÀzÀ DPÁgÀ¢AzÀ¯Éà CzÀgÀ ¨sÀæªÀÄt ªÉÃUÀzÀ §UÉÎ
ªÀiÁ»w zÉÆgÀPÀÄvÀÛzÉ. UÀÄgÀÄ ªÀÄvÀÄÛ ±À¤UÀæºÀUÀ¼À
¨sÀæªÀÄt ªÉÃUÀ ºÉZÀÄÑ. AiÀÄÄgÉãÀ¸ï, £É¥ÀÆÑ£ï,
¨sÀÆ«Ä ªÀÄvÀÄÛ ªÀÄAUÀ¼ÀUÀ¼À ªÉÃUÀªÀÇ ºÉZÀÄÑ. F
CA±À CªÀÅUÀ¼À DPÁgÀzÀ¯Éèà ªÀåPÀÛªÁUÀÄvÀÛzÉ.
¤zsÁ£ÀªÁV ¸ÀÄvÀÄÛªÀ ±ÀÄPÀæ ªÀÄvÀÄÛ ZÀAzÀæUÀ¼À°è F
¥ÀjuÁªÀÄ PÀAqÀħgÀĪÀÅ¢®è.
The shapes of planets are determined
mainly by their own gravity but are also
affected by their rotation. Rotation is
an inherent property of all celestial
bodies. Some are fast rotators like
Jupiter and Saturn. Because of the
fast rotation the planets are slightly
elongated along the equator. Hence,
it appears flattened at the poles. This
shape is called a geoid. This is
demonstrated here with a rotating
frame. The circular strip bulges in the
middle as the frame is rotated.
Amount of bulging of the planet is a
measure of the speed of rotation as
shown by the exhibit here.
Planets Uranus, Neptune and Earth
also show this effect.
The slow
rotators like Venus and Moon do not
show noticeable bulging.
AiÀÄÄgÉãÀ¸ï UÀæºÀzÀ ¥Àj¨sÀæªÀÄuÉ ªÀÄvÀÄÛ DªÀvÀð£É
Revolution and Rotation of Uranus
¸ËgÀªÀÇåºÀzÀ ºÉaÑ£À UÀæºÀUÀ¼À DªÀvÀð£ÀzÀ
CPÀëUÀ¼ÀÄ PÀPÁëvÀ®PÉÌ ¸ÀĪÀiÁgÁV ®A§ªÁV
EgÀÄvÀÛªÉ. ¨sÀÆ«ÄAiÀÄzÀÄ 66 1/20 UÀ¼ÀµÀÄÖ
NgÉAiÀiÁVzÉ. AiÀÄÄgÉãÀ¸ï UÀæºÀzÀÄÝ E£ÀÆß
ªÉʲµÀÖöå ¥ÀÆtðªÁVzÉ. PÀPÁëvÀ®PÉÌ PÉêÀ®
JAlÄ rVæUÀ¼ÀµÀÄÖ NgÉAiÀiÁVzÉ. DzÀÝjAzÀ
DªÀvÀð£ÀzÀ CPÀëªÀÅ AiÀÄÄgÉãÀ¸ï ªÀµÀðzÀ°è
(CAzÀgÉ 84 ¨sÀÆ ªÀµÀðUÀ¼ÀÄ) JgÀqÀÄ ¨Áj
¸ÀÆAiÀÄð£ÀvÀÛ ZÁagÀÄvÀÛzÉ.
DzÀÝjAzÀ
AiÀÄÄgÉãÀ¸ï UÀæºÀzÀ zsÀÄæªÀzÀ ªÉÄÃ¯É ¤AvÀªÀjUÉ
¢£ÀzÀ CªÀ¢ü ªÀÄvÀÄÛ ªÀµÀðzÀ CªÀ¢ü JgÀqÀÆ
MAzÉà J£ÀߧºÀÄzÀÄ.
For most of the planets in the Solar
System rotation axes are almost
perpendicular to the orbital plane.
However, for Earth itself the rotation
is tilted by 66½0 to the orbital plane.
Planet Uranus is a more extreme
exception. Its rotation axis is 80 off
the orbital plane ie., almost along the
plane.
The rotation axis points
almost to the Sun twice during the
planet's one revolution in 84 years.
Therefore the length of the day and
the year are same on the pole of
Uranus.
Many other similar
interesting circumstances occur on
Uranus.
¸ËgÀPÀ¯ÉUÀ¼ÀÄ
Sunspots
¸ËgÀ P À ¯ É U À ¼ À Ä ¸À Æ AiÀ Ä ð©A§zÀ PÀ ¥ À Ä à
ªÀÄZÉÑUÀ¼ÀAvÉ PÁtĪÀŪÀÅ. CªÀÅ ¸ÀÄvÀÛ°£À
¥ÀæzÉñÀQÌAvÀ ¸ÀĪÀiÁgÀÄ 2000 rVæUÀ¼ÀµÀÄÖ
PÀrªÉÄ GµÀÚvÉAiÀÄ°ègÀĪÀÅzÀjAzÀ PÀ¥ÁàV
PÁtĪÀŪÀÅ.
Sunspots appear as dark
blemishes on the disc of the Sun.
They are about 2000 degree cooler
than the surrounding region; hence
they appear dark.
¸ÀÆAiÀÄð©A§ªÀ£ÀÄß zÀÆgÀzÀ±ÀðPÀzÀ ªÀÄÆ®PÀ
vÉgÉAiÀÄ ªÉÄÃ¯É ªÀÄÆr¹ ¸ËgÀPÀ¯ÉUÀ¼À£ÀÄß
£ÉÆÃqÀ§ºÀÄzÀÄ.
The sunspots can be observed by
projecting the Sun's image on a
screen, with the help of a
telescope.
PÀ¯ÉUÀ¼ÀÄ ¸ÀĪÀiÁgÀÄ 10000 Q.«ÄÃ. UÀ¼ÀµÀÄÖ
zÉÆqÀØzÁVAiÀÄÆ EgÀ§ºÀÄzÀÄ. ºÀ£ÉÆßAzÀÄ
ªÀµÀðUÀ½UÉƪÉÄä EªÀÅUÀ¼À ¸ÀASÉå UÀjµÀתÀ£ÀÄß
ªÀÄÄlÄÖvÀÛzÉ. EzÀ£ÀÄß ¸ËgÀZÀPÀæ JAzÀÄ
PÀgÉAiÀÄÄvÁÛgÉ. ¸ÀÆAiÀÄð£À CAvÀgÁ¼ÀzÀ°è
GAmÁUÀĪÀ PÁAvÀPÉëÃvÀæzÀ ªÀåvÁå¸ÀUÀ¼ÀÄ
»ÃUÉ PÀ¯ÉUÀ¼À£ÀÄß GAlÄ ªÀiÁqÀÄvÀÛzÉ.
A sunspot can be as large as 10000
kms across. The number of spots
varies with a period of 11 years
which is known as the Solar Cycle.
Sunspots are due to changes in
magnetism inside the Sun.
MAzÀÄ ¢£ÀPÉÌ JµÀÄÖ ªÀµÀðUÀ¼ÀÄ?
How Many Years in a Day?
§ÄzsÀ UÀæºÀzÀ DªÀvÀð£ÁªÀ¢ü ªÀÄvÀÄÛ
¥À æ z À Q ë u ÁªÀ ¢ ü U À ¼ À Ä «±É à µÀ ª ÁV
¸ÀAAiÉÆÃfvÀªÁVªÉ. ¨sÀÆ«ÄAiÀÄ F
CªÀ¢üUÀ¼ÀÄ PÀæªÀĪÁV MAzÀÄ ¢£À ªÀÄvÀÄÛ
365 ¢£ÀUÀ¼ÀÄ. §ÄzsÀUÀæºÀPÉÌ PÀæªÀĪÁV
56 ¨sÀÆ ¢£ÀUÀ¼ÀÄ ªÀÄvÀÄÛ 88 ¨sÀÆ
¢£ÀUÀ¼ÀÄ. F PÁgÀt §ÄzsÀzÀ MAzÀÄ ¢£À
JAzÀgÉ ªÀÄzsÀågÁwæ¬ÄAzÀ ªÀÄÄA¢£À
ªÀÄzsÀågÁwæAiÀÄ ªÀgÉV£À CªÀ¢ü 176 ¨sÀÆ
¢£ÀUÀ¼ÁUÀÄvÀÛªÉ. CAzÀgÉ MAzÀÄ §ÄzsÀ
¢£ÀPÉÌ JgÀqÀÄ §ÄzsÀ ªÀµÀðUÀ¼ÀÄ.
Planet Mercury has a very
different combination of rotation
and revolution period as
compared to the Earth. They are
56 Earth days and 88 Earth days
respectively (for the Earth, they
are one day and 365 days
respectively). This leads to a very
interesting consequence. A
“Mercurian day” ie., the time
interval between two successive
noons works out to be 176 Earth
days. Thus a Mercurian day is
equal to two Mercurian years.
C¸ÉÆÖçïÉèï
Astrolabe
£Á«PÀjUÉ CvÀåAvÀ G¥ÀAiÉÆÃVAiÀiÁzÀ F
¸Ázs À £ À ±À v À ª À i Á£À U À ¼ À »A¢¤AzÀ ® Æ
§¼À P É A iÀ Ä °è z É . ªÀ Ä Æ®¨s À Æ vÀ ª ÁzÀ UÀ t  v À
¸ÀÆvÀæUÀ¼À DzsÁgÀzÀ ªÉÄÃ¯É gÀavÀªÁzÀ EzÀ£ÀÄß
C£ÉÃPÀ GzÉÝñÀUÀ½UÉ §¼À¸À§ºÀÄzÀÄ.
• AiÀiÁªÀÅzÉà ¸ÀܼÀzÀ CPÁëA±ÀªÀ£ÀÄß
C¼ÉAiÀÄĪÀÅzÀÄ. »A¨sÁUÀzÀ°è PÉÆnÖgÀĪÀ
JgÀqÀÄ gÀAzsÀæUÀ¼À ¥ÀnÖ¬ÄAzÀ zsÀÄæªÀ
£ÀPÀëvÀæªÀ£ÀÄß «ÃQë¹. EzÀ£ÀÄß
w½AiÀħºÀÄzÀÄ.
• AiÀiÁªÀÅzÉà £ÀPÀëvÀæUÀ¼À ¸ÁÜ£À
¤zÉÃð±À£ÀUÀ¼À£ÀÄ C¼ÉÀAiÀħºÀÄzÀÄ.
• ¸ÁÜ£À ¤zÉÃð±ÀPÀUÀ½AzÀ gÁwæAiÀÄ ¸ÀªÀÄAiÀÄ
PÀAqÀÄ»rAiÀħºÀÄzÀÄ
• ¸ÀÆAiÀÄð£À ¸ÁÜ£ÀªÀ£ÀÄß C¼ÉzÀÄ ºÀUÀ°£À
¸ÀªÀÄAiÀĪÀ£ÀÄß ¯ÉPÀÌ ºÁPÀ§ºÀÄzÀÄ
• ¸ÀÆAiÉÆÃðzÀAiÀÄ ªÀÄvÀÄÛ ¸ÀÆAiÀiÁð¸ÀÛUÀ¼À
¸ÀªÀÄAiÀÄUÀ¼À£ÀÄß ¯ÉPÀÌ ºÁPÀ§ºÀÄzÀÄ
The navigators of earlier days used
to find their location on the Earth
with the help of stars. Astrolabe is
an instrument devised for this
purpose. It is based on geometrical
formulae. It can be used for various
purposes such as
• Measuring the latitude of a
place; this is done by viewing
the pole star through the
viewing arrangement at the
rear side.
• Estimating the time by
measuring the altitude and
azimuth of Sun.
• Measuring the position of stars
• Estimating the local time by
measuring the altitude and
azimuth of bright stars
• Finding the rise and set time of
Sun, planets and stars.
±ÀÄPÀæUÀæºÀzÀ DªÀvÀð£À
Rotation of Venus
¸ËgÀªÀÇåºÀzÀ J¯Áè UÀæºÀUÀ¼ÀÄ ¸ÀÆAiÀÄð£À£ÀÄß
MAzÉà ¢QÌ£À°è ¸ÀÄvÀÄÛvÀÛªÉ. ºÉaÑ£À UÀæºÀUÀ½UÉ
DªÀvÀð£ÉAiÀÄ ¢PÀÆÌ CzÉà DVzÉ. AiÀÄÄgÉãÀ¸ï
ªÀÄvÀÄÛ ±ÀÄPÀæ ªÀiÁvÀæ EzÀPÉÌ C¥ÀªÁzÀUÀ¼ÀÄ.
E°ègÀĪÀ ªÀiÁzÀj ±ÀÄPÀæUÀæºÀzÀ DªÀvÀð£ÉAiÀÄÄ
¨sÀÆ«ÄAiÀÄzÀQÌAvÀ «gÀÄzÀÞªÁVzÉ JAzÀÄ
vÉÆÃj¸ÀÄvÀÛzÉ.
DzÀÝjAzÀ ±ÀÄPÀæUÀæºÀzÀ
ªÉÄð¤AzÀ gÁwæAiÀÄ DPÁ±ÀªÀ£ÀÄß £ÉÆÃrzÀgÉ
£À P À ë v À æ ¥ À Ä AdUÀ ¼ À Ä «gÀ Ä zÀ Þ ¢QÌ £ À ° è
wgÀÄUÀÄwÛªÉAiÉÆà C¤ß¸ÀÄvÀÛzÉ.
E£ÉÆßAzÀÄ
ªÉʲµÀÖöåªÉAzÀgÉ DªÀvÀð£É ªÀÄvÀÄÛ ¥Àj¨sÀæªÀÄuÉAiÀÄ
CªÀ¢üUÀ¼ÀÄ ¸ÀĪÀiÁgÁV MAzÉÃ. (224 ªÀÄvÀÄÛ
243 ¨sÀÆ ¢£ÀUÀ¼ÀÄ). CAzÀgÉ ±ÀÄPÀæ ¸ÀÆAiÀÄðUÀ¼À ªÀåªÀ¸ÉÜ ¨sÀÆ«Ä-ZÀAzÀæ£ÀAvÉAiÉÄÃ
J£ÀߧºÀÄzÀÄ.
All planets in the Solar System
revolve around the Sun in the
same direction. For most of the
planets the rotation directions are
also the same. Rotations of
Uranus and Venus are two
exceptions. This model demonstrates the rotation of Venus,
which is opposite to its direction of
revolution. Therefore the motion
of constellation in the night sky on
Venus will be opposite to that on
the Earth. Another interesting
aspect is that the rotation and
revolution periods are 224 days
243 days comparable.
Venus-Sun system is roughly
similar to the Earth-Moon system.
The model demonstrates this fact
zÀæªÀ zÀ¥Àðt zÀÆgÀzÀ±ÀðPÀzÀ vÀvÀé
Principle of Liquid Mirror Telescopes
zÀÆgÀzÀ±ÀðPÀUÀ½UÉ ¥ÀgÀªÀ®AiÀÄzÀ DPÁgÀzÀ
PÀ£ÀßrUÀ¼À£ÀÄß §¼À¸ÀĪÀÅzÀjAzÀ C£ÉÃPÀ
G¥À A iÉ Æ ÃUÀ U À ½ ªÉ . AiÀ i ÁªÀ Å zÁzÀ g À Æ
zÀæªÀªÀ£ÀÄß ¹°AqÀgï£À°è wgÀÄV¹zÁUÀ
CzÀgÀ ªÉÄîàzÀgÀ ¥ÀgÀªÀ®AiÀÄzÀ DPÁgÀ
¥À q É A iÀ Ä ÄvÀ Û z É . E°è F vÀ v À é ª À £ À Ä ß
¤gÀƦ¸À¯ÁVzÉ. wgÀÄV¸ÀĪÀ ªÉÃUÀªÀ£ÀÄß
ªÀåvÁå¸À ªÀiÁr ¥ÀgÀªÀ®AiÀÄ DPÁgÀzÀ
£Á©üAiÀÄ ¸ÁÜ£ÀªÀ£ÀÄß §zÀ°¸À§ºÀÄzÀÄ. F
vÀ v À é ª À £ À Ä ß zÀ Æ gÀ z À ± À ð PÀ U À ½ UÉ FUÀ
§¼À¸À¯ÁUÀÄwÛ z É . E°è ¹°AqÀgï
AiÀiÁªÁUÀ®Æ ²gÉÆéAzÀĪÀ£ÀÄß ªÀiÁvÀæ
£ÉÆÃqÀ§®ÄèzÀÄ. EzÉÆAzÉà F
zÀÆgÀzÀ±ÀðPÀzÀ C£Á£ÀÄPÀÆ®vÉ.
The parabolic surface has many
advantages when used for
telescopic mirrors. When a liquid
is rotated in a cylinder, it assumes
a parabolic surface. This principle
is used in liquid mirror telescopes.
This model here demonstrates the
effect of rotation on a liquid
surface. Depending on the speed
of rotation the focus of the
parabolic surface can be
changed. The only disadvantage
of this type of telescope is that it
can see only the zenith since it has
to be always vertical.
±À¤UÀæºÀzÀ GAUÀÄgÀUÀ¼ÀÄ
Rings of Saturn
±À ¤ UÀ æ º À z À GAUÀ Ä gÀ U À ¼ À Ä ¸À t Ú zÀ Æ gÀ zÀ±ÀðPÀUÀ¼À°èAiÀÄÆ ¸ÀÄAzÀgÀªÁV PÁtĪÀŪÀÅ.
zÀÆgÀzÀ±ÀðPÀzÀ ªÀÄÆ®PÀ C£ÉÃPÀ ªÀµÀðUÀ¼À PÁ®
«ÃPÀ ë u É £À q É ¹ zÀ g É GAUÀ Ä gÀ U À ¼ À Ä PÀ æ ª É Ä Ãt
vÉ ¼ À î U ÁUÀ Ä wÛ z À Ý A vÉ CxÀ ª Á zÀ ¥ À à ª ÁUÀ Ä wÛ z À Ý A vÉ
PÁtĪÀÅzÀÄ. MªÉÆäªÉÄä ªÀiÁAiÀĪÁzÀAvÉAiÀÄÆ
C¤ß¸À§ºÀÄzÀÄ. zÀÆgÀzÀ±ÀðPÀUÀ¼À£ÀÄß §¼À¸À®Ä
DgÀA©ü¹zÀ ºÉƸÀzÀgÀ°è F §UÉAiÀÄ WÀl£ÉUÀ¼ÀÄ
MUÀlÄUÀ¼ÀAvÉ vÉÆÃjzÀªÀÅ. ºÁ¯ÉAr£À Qæ²ÑAiÀÄ£ï
ºÉÊUÉ£ïì (1629-1695) EzÀPÉÌ ¸ÀªÀÄ¥ÀðPÀªÁzÀ GvÀÛgÀ
MzÀV¹zÀ£ÀÄ. £ÀªÀÄä zÀ馅 gÉÃSÉUÉ GAUÀÄgÀUÀ¼ÀÄ
NgÉAiÀiÁVªÉ. ºÀ¢£ÉÊzÀÄ ªÀµÀðUÀ½UÉƪÉÄä ¨sÀÆ«Ä
GAUÀÄgÀUÀ¼À vÀ®zÀ ªÀÄÆ®PÀ ºÁzÀÄ ºÉÆÃUÀÄvÀÛzÉ;
DUÀ CªÀÅUÀ¼À ¥Á±Àéð £ÉÆÃl zÉÆgÀPÀÄvÀÛzÉ. DUÀ
GAUÀ Ä gÀ U À ¼ À Ä vÉ ¼ À î £ É A iÀ Ä UÉ g É A iÀ Ä ºÁUÉ
PÁtÄvÀ Û ª É A iÀ i ÁzÀ g À Æ Cw zÉ Æ qÀ Ø zÀ Æ gÀ zÀ±ÀðPÀzÀ°èAiÀÄÆ PÀÆqÀ UÀÄgÀÄw¸À®Ä ¸ÁzsÀåªÁUÀzÀÄ.
F CªÀPÁ±ÀªÀ£ÀÄß G¥ÀAiÉÆÃV¹ GAUÀÄgÀUÀ¼À
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2009gÀ°è CzÀȱÀåªÁUÀĪÀŪÀÅ.
The rings of Saturn are visible even
through a small telescope. As you
watch the planet over a number of
years, the rings gradually appear
thinner and thinner or vice versa.
There are occasions when they
cannot be seen at all. This was a
puzzle for the early telescope
viewers. It was resolved by Dutch
astronomer Christian Huygens
(1629-1695). The rings are not visible
when they are viewed edge on. This
happens once in fifteen years. The
edge on view of the rings renders
them as a thin line barely
recognizable even through a very
large telescope. This offers an
opportunity to identify small satellites
which otherwise are lost in the glare
of rings.
We had seen the disappearance in
1995; the next one will be in 2009.
IÄvÀĪÀiÁ£ÀUÀ½UÉ PÁgÀt
The reasons for seasons
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IÄvÀĪÀiÁ£ÀUÀ½UÉ PÁgÀt. F CPÀëªÀÅ PÀPÁëvÀ®PÉÌ 66½°
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zÀQët zsÀÄæªÀPÉÌ E®è. r¸ÉA§gï£À°è EzÀPÉÌ vÀ¢égÀÄzÀÞ. G½zÀ
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GAmÁUÀÄvÀÛªÉ JA§ÄzÀ£ÀÄß F ªÀiÁzÀj «ªÀj¸ÀÄvÀÛzÉ.
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d£ÀªÀj 4gÀAzÀÄ ¸ÀÆAiÀÄð- ¨sÀÆ«Ä CAvÀgÀ PÀ¤µÀ× CAzÀgÉ
¸ÀĪÀiÁgÀÄ 148,000,000 Q«Äà ; dįÉÊ 4gÀAzÀÄ F
CAvÀgÀ UÀjµÀ× CAzÀgÉ ¸ÀĪÀiÁgÀÄ 152,000,000 Q«ÄÃ.
zÀÆgÀzÀ°èAiÀÄ ±ÉÃPÀqÁ 2gÀµÀÖgÀ F ¸ÀtÚ ªÀåvÁå¸À
IÄvÀÄUÀ½UÉ PÁgÀtªÀ®è.
The Earth completes one revolution around the
Sun in one year. As Kepler stated all planetary
orbits are elliptical. There is a widespread
misconception that seasons occur on the Earth
because Earth's orbit is elliptical. Actually
seasons are caused by the tilt of the Earth's
rotation axis. Rotation of Earth causes
successions of days and nights. Earth's axis of
rotation is at an angle of 66 ½ 0 to the plane of
Earth's orbit around Sun and its orientation in
space remains fixed as Earth revolves around
the Sun. The seasons are caused due to this tilt
in the rotation axis. Also due to this, at different
latitudes the Sun is seen at different elevations
and for different durations. Sun's path in the sky
also appears to change throughout the year for
the same reason. In June, the Arctic regions get
sunshine while the Antarctic regions do not. n
December it is opposite. For other regions
similar changes occur but are not as extreme.
These are the different seasons. The model
explains that the basic reason for this is the
inclination of the Earth's rotation axis. The
elliptical orbit does not cause seasons, as is
commonly believed. On January 4th every year
the Earth-Sun distance is a minimum
(~148,000,000km) and on July 4th it is a
maximum (~152,000,000km). This variation
cannot cause the seasons because it amounts to
only 2% change.
Science in Action – Astronomy
January 23 – 25, 2009
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vÀvÀéªÀ£ÀÄß ¤gÀƦ¸ÀÄvÀÛªÉ. C¼ÀvÉUÉ vÀPÀÌAvÉ E®è.
Over view
It is difficult to make of the solar system to
scale since the distances and sizes vary
enormously. Our size is insignificant
compared to that of the Earth. The size of
the Earth is insignificant compared to that
of the Sun. As the Earth rotates it appears
to us that the celestial body has to returned
to the same position in the sky
approximately after 24 hours. This is
called the diurnal motion. The earth goes
round the sun; this motion is termed
revolution. Seasons sun's changes in
position is termed the annual motion. This
model depicts these motions. The
constellations also show diurnal motion
but not annual motion.
Each model here is designed to illustrate a
specific concept. They are not to scale.