You can see the constellation Cancer in the northern hemisphere during the spring months, specifically from late March to early June.

Here's a more detailed explanation:

* Best viewing time: The best time to see Cancer is around mid-April when it is highest in the sky around midnight.

* Location: Look for Cancer near the constellation Gemini, which is easily recognizable by its two bright stars, Castor and Pollux. Cancer sits directly above Gemini and to the east of Leo.

* Visibility: Cancer is a faint constellation, so it's not easy to spot. However, if you have a clear dark sky, you might be able to see its brightest star, Acubens.

* Other factors: The visibility of Cancer can also be affected by light pollution and weather conditions.

Remember, the exact dates and times may vary slightly depending on your location. You can use a stargazing app or website to find the best viewing times for your area.