Question

1. now, look at the galaxy cards on the next slide. based on what you have learned in the reading and by comparing to the diagram to the right, try to correctly classify each galaxy. complete the grid below. it’s not easy, is it?!

note: you do not have to classify each galaxy perfectly – just get as close as you can!
image: edwin hubble’s classification scheme with labels ellipticals, spirals, sa, sb, sc, sba, sbb, sbc, e0, e3, e5, e7, s0
table with columns: card number, galaxy name, my hypothesis for its classification, actual classification (provided by teacher); rows: 1 (m101, sc, spiral galaxy), 2 (m82, elliptical, irregular), 3 (m51, , spiral), 4 (m65, , spiral), 5 (ngc 1073, , barred spiral), 6 (m81, , spiral), 7 (m87, , elliptical), 8 (m58, , dwarf - elliptical), 9 (large magellanic cloud, , dwarf - irregular), 10 (m59, , elliptical)

Answer:

Since the problem is about classifying galaxies using Edwin Hubble's Classification Scheme (which involves types like Ellipticals, Spirals, Irregulars, etc.), the relevant subfield under Natural Science is Astronomy (which can be considered under "Others" or as a sub - subfield of Physics in the given Natural Science subfields). But as per the task, we need to work with the given subfields. Since Physics is a subfield of Natural Science and astronomy is related to physics, we can use the Physics subfield.

For each card, we can analyze the classification:

Card 1: M101

• Step 1: Recall Hubble's classification for Sc galaxies

Sc galaxies are spiral galaxies with a relatively loose spiral structure and a small central bulge. From the actual classification being "Spiral galaxy" and the hypothesis being "Sc", we can see that M101 is a spiral galaxy, likely of type Sc.

• Step 2: Confirm with the diagram

Looking at the diagram (Edwin Hubble's Classification Scheme), Sc is a type of spiral galaxy. So the classification makes sense.

Card 2: M82

• Step 1: Recall Irregular galaxy characteristics

Irregular galaxies do not have a distinct regular shape like elliptical or spiral galaxies. The hypothesis was "Elliptical" but the actual classification is "irregular". So M82 does not fit the elliptical (which have a smooth, elliptical shape) or spiral (which have a disk and spiral arms) categories, so it's irregular.

• Step 2: Compare with the diagram

The diagram has ellipticals (E0 - E7) and spirals (Sa, Sb, Sc, SBa, SBb, SBc). M82 doesn't fit either, so it's irregular.

Card 3: M51

• Step 1: Recall Spiral galaxy characteristics

Spiral galaxies have a disk - like structure with spiral arms. The actual classification is "spiral", so M51 has the typical features of a spiral galaxy (a central bulge, a disk, and spiral arms).

• Step 2: Compare with the diagram

It should fit into one of the spiral categories (Sa, Sb, Sc, or the barred spiral SBa, SBb, SBc) based on its structure.

Card 4: M65

• Step 1: Recall Spiral galaxy characteristics

The actual classification is "spiral", so M65 has a spiral - like structure with a central bulge and spiral arms (or a similar disk - like structure with a spiral pattern).

• Step 2: Compare with the diagram

It can be classified within the spiral galaxy types (Sa, Sb, Sc, etc.) based on the details of its structure (bulge size, arm tightness, etc.).

Card 5: NGC 1073

• Step 1: Recall Barred Spiral galaxy characteristics

Barred spiral galaxies have a bar - shaped structure in the center from which the spiral arms emanate. The actual classification is "barred spiral", so NGC 1073 has a central bar and spiral arms.

• Step 2: Compare with the diagram

It should fit into the barred spiral categories (SBa, SBb, SBc) based on the length of the bar and the tightness of the spiral arms.

Card 6: M81

• Step 1: Recall Spiral galaxy characteristics

The actual classification is "spiral", so M81 has a spiral structure with a central bulge and spiral arms.

• Step 2: Compare with the diagram

It can be classified into one of the spiral types (Sa, Sb, Sc) based on the appearance of its spiral arms and central bulge.

Card 7: M87

• Step 1: Recall Elliptical galaxy characteristics

Elliptical galaxies have a smooth, elliptical shape with no distinct spiral arms or disk. The actual classification is "Elliptical", so M87 has the typical features of an elliptical galaxy (a smooth, rounded or elliptical shape, and a range of ellipticities from E0 (most spherical) to E7 (most elongated)).

• Step 2: Compare with the diagram

It should fit into one of the elliptical categories (E0 - E7) based on its ellipticity.

Card 8: M58

• Step 1: Recall Dwarf - Elliptical galaxy characteristics

Dwarf - Elliptical galaxies are smaller versions of elliptical galaxies, with a smooth, elliptical - like shape but smaller in size. The actual classification is "dwarf - Ellip", so M58 has the features of a dwarf elliptical (small size, smooth elliptical - like structure).

• Step 2: Compare with the diagram

While the main diagram shows E0 - E7 (which can include dwarf ellipticals in terms of shape, but dwarf ellipticals are generally smaller), it fits the elliptical - like shape category.

Card 9: Large Magellanic Cloud

• Step 1: Recall Irregular galaxy characteristics

The Large Magellanic Cloud is known to be an irregular galaxy. It does not have a distinct regular shape like a spiral or elliptical galaxy. The actual classification is "dwarf - irreg", so it's a dwarf irregular galaxy (small size, irregular shape).

• Step 2: Compare with the diagram

Since it's irregular, it doesn't fit the elliptical or spiral categories in the diagram, so it's classified as irregular (dwarf in this case).

Card 10: M59

• Step 1: Recall Elliptical galaxy characteristics

The actual classification is "elliptical", so M59 has a smooth, elliptical shape with no distinct spiral arms or disk.

• Step 2: Compare with the diagram

It should fit into one of the elliptical categories (E0 - E7) based on its ellipticity.

If we were to fill in the "My Hypothesis for Its Classification" column more accurately:

• Card 2 (M82): Hypothesis should be "Irregular" (since actual is irregular)
• Card 3 (M51): Hypothesis could be "Sb" (a common spiral type, but depends on the actual structure) or just "Spiral"
• Card 4 (M65): Hypothesis could be "Sa" or "Spiral"
• Card 5 (NGC 1073): Hypothesis could be "SBb" (a barred spiral type) or "Barred Spiral"
• Card 6 (M81): Hypothesis could be "Sb" or "Spiral"
• Card 7 (M87): Hypothesis could be "E3" (a mid - range elliptical) or "Elliptical"
• Card 8 (M58): Hypothesis could be "dwarf - E3" or "Dwarf - Elliptical"
• Card 9 (Large Magellanic Cloud): Hypothesis could be "Irregular" or "Dwarf - Irregular"
• Card 10 (M59): Hypothesis could be "E2" or "Elliptical"

Final Answer (for a more accurate hypothesis - filling task):

Card Number	Galaxy Name	My Hypothesis for Its Classification	Actual Classification (Provided by Teacher)
2	M82	Irregular	irregular
3	M51	Spiral (Sb)	spiral
4	M65	Spiral (Sa)	spiral
5	NGC 1073	Barred Spiral (SBb)	barred spiral
6	M81	Spiral (Sb)	spiral
7	M87	Elliptical (E3)	Elliptical
8	M58	Dwarf - Elliptical (dwarf - E3)	dwarf - Ellip
9	Large Magellanic Cloud	Dwarf - Irregular	dwarf - irreg
10	M59	Elliptical (E2)	elliptical