# What is the hottest you can make a focused beam of sunlight?

**URL:** <https://boards.straightdope.com/t/what-is-the-hottest-you-can-make-a-focused-beam-of-sunlight/232700>\
**Category:** Factual Questions\
**Created:** [March 5, 2004, 2:54pm UTC](https://boards.straightdope.com/t/what-is-the-hottest-you-can-make-a-focused-beam-of-sunlight/232700 "2004-03-05T14:54:51Z")\
**Posts on this page:** 1\
**Page:** 3

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**Author:** ![umop\_ap\_sdn](https://avatars.discourse-cdn.com/v4/letter/u/dbc845/32.png) [@umop\_ap\_sdn](https://boards.straightdope.com/u/umop_ap_sdn)\
**Post date:** [March 6, 2004, 5:32am UTC](https://boards.straightdope.com/t/what-is-the-hottest-you-can-make-a-focused-beam-of-sunlight/232700/41 "2004-03-06T05:32:05Z")

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> [@Pleonast](#):
>
> (and what color does zinc burn?)

Well zinc makes a bright blue electrical spark, and its salts color non-luminous flames blue, so it should burn blue. Or white if it got hot enough to incandesce like aluminum and magnesium do, but it takes a lot of heat to ignite aluminum or magnesium (and the result would look like one of those sparkler fireworks things).

OK **Elysian** now I’m curious 🙂 - what color and how intense was the flame?

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