Solar and Lunar Eclipses: Causes and Differences
In the geography section of REET Level 2 Social Studies, eclipses are a basic astronomy topic, with direct questions on how and when solar and lunar eclipses form. This page explains the astronomical process behind both eclipses, the difference between umbra and penumbra, and a simple classroom activity.
- No direct REET 2024 question, syllabus-based
- Class 6-8 level
- 8 min read
How REET asks this topic
We don't have a verified question on eclipses from the REET 2024 paper, so we're not showing a made-up old question here. This note is based on the wording of the REET Level 2 Social Studies (Geography) syllabus and NCERT Class 6-level concepts such as 'The Earth: Our Habitat'. Since this topic is part of the syllabus, a direct question on the astronomical process or the types of eclipses could appear in a future paper.
Solar eclipse: when the moon comes between the sun and the earth
A solar eclipse happens when the moon comes exactly between the sun and the earth, casting the moon's shadow on part of the earth — this can only happen on a new-moon day, when the moon sits between the sun and the earth. Because the moon is much smaller than the earth, its shadow falls on only a very small part of the earth — which is why a solar eclipse is visible from only a limited area of the earth.
A solar eclipse can be of three types — a total solar eclipse (when the moon completely covers the sun), a partial solar eclipse (when the moon covers only part of the sun), and an annular eclipse (when the moon, being at its farthest point from the earth in its orbit, appears smaller than the sun, leaving a bright ring visible around it).
Lunar eclipse: when the earth comes between the sun and the moon
A lunar eclipse happens when the earth comes between the sun and the moon, casting the earth's shadow on the moon — this can only happen on a full-moon day, when the earth sits between the sun and the moon. Because the earth is bigger than the moon, its shadow is also bigger, so a lunar eclipse is visible from the entire half of the earth where it is night at the time — this is why a lunar eclipse can be seen from a much larger area, and for much longer, than a solar eclipse.
A solar eclipse doesn't happen at every new moon, and a lunar eclipse doesn't happen at every full moon, because the moon's orbit is tilted at about 5 degrees to the earth's orbit (the ecliptic). An eclipse only forms when the sun, earth and moon come nearly into a straight line — a situation that arises only a limited number of times a year.
A lunar eclipse can also be total or partial, depending on whether the moon enters the earth's umbra fully or only partly. During a total lunar eclipse, the moon doesn't turn completely black — instead, it appears a faint coppery-red, because of sunlight bent through the earth's atmosphere reaching it — which is why it is sometimes called a 'blood moon'.
Solar eclipse versus lunar eclipse
| Basis | Solar eclipse | Lunar eclipse |
|---|---|---|
| When it happens | New moon | Full moon |
| What comes in between | The moon (between the sun and the earth) | The earth (between the sun and the moon) |
| What the shadow falls on | The earth | The moon |
| Area of visibility | A limited, small area | The entire night-side half of the earth (a large area) |
| Safe to view directly? | No, dangerous without special protective glasses | Yes, safe to view with the naked eye |
A total eclipse is visible from the umbra (the full shadow) region, and a partial eclipse from the penumbra (the partial shadow) region.
Key astronomical terms
- Umbra
- The darkest, fully shadowed part of a shadow — a total eclipse is visible from this region.
- Penumbra
- The lighter, partially shadowed outer part of a shadow — a partial eclipse is visible from this region.
- New moon
- The date when the moon sits between the sun and the earth and is not visible from earth — a possible date for a solar eclipse.
- Full moon
- The date when the earth sits between the sun and the moon and the moon appears fully round — a possible date for a lunar eclipse.
How to teach this to children
Activity
Build a model with a large ball (the earth), a small ball (the moon) and a torch (the sun) — when the small ball comes between the big ball and the torch, that's a solar eclipse; when the big ball comes in between, that shows a lunar eclipse.
Teaching aid
Putting up a simple diagram in class showing umbra and penumbra in different colours gives children a clear picture of both types of eclipse.
Common misconception
Children often believe an eclipse happens because clouds cover the sun or moon, or see it as a bad omen. Explain the scientific cause (the relative position of the earth, moon and sun) clearly and sensitively, without mocking any family beliefs.
Assessment
Have children draw a solar and a lunar eclipse showing the correct positions of the sun, earth and moon — this is a visual way to check whether the concept is correctly understood.
Connecting to life skills
While teaching eclipses scientifically, also teach safety rules (such as never looking at a solar eclipse with the naked eye) — this ties the topic to a practical life skill as well.
Memory trick
Remember — 'moon in the middle means solar eclipse' (when the moon comes between the sun and the earth) and 'earth in the middle means lunar eclipse' (when the earth comes between the sun and the moon). Also, 'full moon-lunar, new moon-solar' — remembering this order makes date-related questions easy. And remember: a solar eclipse is visible from a small area, a lunar eclipse from a large one.
Practice questions
Question 1
A solar eclipse occurs in which astronomical position?
- Aचंद्रमा सूर्य व पृथ्वी के बीच आए
- Bपृथ्वी सूर्य व चंद्रमा के बीच आए
- Cसूर्य पृथ्वी व चंद्रमा के बीच आए
- Dइनमें से कोई नहीं
Explanation
A solar eclipse happens when the moon comes exactly between the sun and the earth, casting the moon's shadow on a limited part of the earth.
Question 2
On which lunar date can a lunar eclipse occur?
- Aअमावस्या
- Bपूर्णिमा
- Cअष्टमी
- Dकिसी भी तिथि को
Explanation
A lunar eclipse can only happen on a full-moon day, when the earth comes exactly between the sun and the moon.
Question 3
Why is a solar eclipse visible from only a very small part of the Earth compared to a lunar eclipse?
- Aक्योंकि सूर्य बहुत बड़ा है
- Bक्योंकि सूर्य ग्रहण रात में होता है
- Cक्योंकि चंद्रमा छोटा होने से उसकी छाया पृथ्वी के केवल एक सीमित भाग पर पड़ती है
- Dक्योंकि पृथ्वी घूमती नहीं है
Explanation
The moon is much smaller than the earth, so its shadow falls on only a small part of the earth, whereas during a lunar eclipse, the earth's larger shadow covers the entire night-side portion.
Question 4
When does an annular (ring-shaped) solar eclipse form?
- Aजब चंद्रमा पृथ्वी के सबसे पास हो
- Bजब पृथ्वी सूर्य के सबसे पास हो
- Cजब चंद्र ग्रहण भी साथ में हो
- Dजब चंद्रमा अपनी कक्षा में पृथ्वी से सबसे दूर होने के कारण सूर्य से छोटा दिखे
Explanation
When the moon is at the farthest point in its orbit from the earth (apogee), it appears smaller than the sun, and the sun's edge shows as a ring — this is called an annular eclipse.
Question 5
What type of eclipse is visible from the umbra region?
- Aपूर्ण ग्रहण
- Bआंशिक ग्रहण
- Cकोई ग्रहण नहीं
- Dवलयाकार ग्रहण ही
Explanation
The umbra is the darkest, fully shadowed part of a shadow, and a total eclipse is visible from this region, while a partial eclipse is visible from the penumbra.
Question 6
A solar eclipse does not occur on every new moon — what is the main reason for this?
- Aसूर्य हर महीने अपनी स्थिति बदलता है
- Bचंद्रमा की कक्षा पृथ्वी की कक्षा से लगभग 5 डिग्री झुकी होती है
- Cपृथ्वी घूमना बंद कर देती है
- Dचंद्रमा का आकार बदल जाता है
Explanation
Because the moon's orbit is tilted at about 5 degrees to the earth's orbit, the sun, earth and moon don't come into a straight line at every new moon, so an eclipse happens only on some new-moon/full-moon dates.
Question 7
Why should a solar eclipse not be viewed directly with the naked eye?
- Aयह कानूनन प्रतिबंधित है
- Bइससे कुछ दिखाई नहीं देता
- Cइससे आँखों को नुकसान पहुँच सकता है
- Dइसका कोई कारण नहीं है
Explanation
The sun's intense rays, viewed directly without proper protective glasses, can permanently damage the retina, which is why special protective glasses or indirect methods are used to view a solar eclipse.
Question 8
A teacher demonstrates an eclipse model in class using a ball and a torch. This activity mainly clarifies which concept?
- Aजलवायु परिवर्तन
- Bभूकंप के कारण
- Cमानसून का आना
- Dसूर्य, पृथ्वी और चंद्रमा की सापेक्ष स्थिति व छाया का बनना
Explanation
A ball-and-torch model directly shows how a shadow forms based on the relative position of the sun, earth and moon — this is the core concept behind an eclipse.
Question 9
Why is a lunar eclipse visible for longer than a solar eclipse?
- Aपृथ्वी की छाया चंद्रमा की छाया से बड़ी होती है
- Bचंद्रमा तेज़ी से घूमता है
- Cसूर्य ग्रहण रात में होता है
- Dइसका कोई निश्चित कारण नहीं है
Explanation
Because the earth is bigger than the moon, its shadow is also bigger, so a lunar eclipse is visible from the entire night-side half of the earth, and for comparatively longer.
Question 10
What should a teacher do if children have a misconception that treats an eclipse as a bad omen?
- Aबच्चों की पारिवारिक मान्यताओं का मज़ाक उड़ाना
- Bवैज्ञानिक कारण स्पष्ट व संवेदनशीलता से समझाना
- Cविषय पर चर्चा ही न करना
- Dबच्चों को डाँटना
Explanation
A teacher should explain the scientific cause of an eclipse clearly and sensitively, without mocking children's family or cultural beliefs, so children can adopt the scientific understanding comfortably.
Frequently asked questions
On which date does a solar eclipse happen?+
A solar eclipse can only happen on a new-moon day, when the moon comes exactly between the sun and the earth.
On which date does a lunar eclipse happen?+
A lunar eclipse can only happen on a full-moon day, when the earth comes exactly between the sun and the moon.
Why doesn't an eclipse happen at every new moon or full moon?+
Because the moon's orbit is tilted at about 5 degrees to the earth's orbit, the sun, earth and moon don't line up at every new/full moon — this alignment is needed, and it doesn't happen every month.
What is the difference between umbra and penumbra?+
The umbra is the darkest, fully shadowed part of a shadow (where a total eclipse is visible), while the penumbra is the lighter, partially shadowed outer part (where a partial eclipse is visible).
How many REET questions come from eclipses?+
This topic is part of the REET Level 2 Social Studies (Geography) syllabus, but REET 2024 had no verified direct question from it — since it's in the syllabus, a question could appear in future.
Why does the moon look red/coppery during a total lunar eclipse?+
Even during a total lunar eclipse, the moon doesn't turn completely black, because sunlight bent through the earth's atmosphere reaches it, giving it a faint red/coppery colour — this is also called a 'blood moon'.
Read next
Official Sources
Change Log
- 17 September 2026 — English page published — mirrors the fact-checked Hindi page, independently bilingual-accuracy checked