NGC 620 is a spiral galaxy located in the constellation Andromeda about 123 million light-years from the Milky Way. It was discovered by the French astronomer Édouard Stephan in 1871.
See also List of NGC objects (1–1000)
References
astronomy
NGC 620 is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand NGC 620 rather than just read about it. In short: NGC 620 is a spiral galaxy located in the constellation Andromeda about 123 million light-years from the Milky Way. It was discovered by the French astronomer Édouard Stephan in 1871.

NGC 620 is a spiral galaxy located in the constellation Andromeda about 123 million light-years from the Milky Way. It was discovered by the French astronomer Édouard Stephan in 1871.
See also List of NGC objects (1–1000)
References

Start with the simplest possible case. Write down what NGC 620 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.
Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to NGC 620 before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.
Typical questions about NGC 620 ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.
NGC 620 is a spiral galaxy located in the constellation Andromeda about 123 million light-years from the Milky Way. It was discovered by the French astronomer Édouard Stephan in 1871.
Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.
Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.
It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on NGC 620.