Although this is a listing of fellowships and scholarships primarily for grad school, there are undergrad scholarships available from some of these agencies — see the descriptions below. It is highly recommended to apply for scholarships throughout your university career, even if you can survive without them. These awards build your undergrad CV and academic reputation and are an asset in future applications.

Be sure to submit your federal aid FAFSA as soon as possible. The deadline is usually in June but there is an earlier deadline for preferential consideration. Additionally, some states have earlier deadlines. The best thing to do is to file the form as soon as you have an idea of where you will apply. You don't need to have been accepted to a grad program already. Just put down the schools you are applying to (or think you will apply to). This will ensure that you can be considered for university funding.

It is very possible that you will not need any external funding at all. However, it's a good idea to apply for fellowships and scholarships. These give you money (of course) but also some freedom and prestige. Fellowship and scholarship applications involve quite a bit of writing- make an appointment at the CU Writing Center for help with it!

The deadlines for graduate school fellowship applications are generally around the same time as grad school application deadlines, so prepare early.

In addition to the following list, here is a general list of fellowships for physics students on the Arizona University website. Massachusetts Institute of Technology's website has a list of fellowships for planetary science students. Astrobites published a helpful list of fellowships for astronomy/astrophysics students.

Fellowships/large awards:

National Science Foundation Graduate Research Fellowship (NSF GRF)

Amount: Tuition plus stipend, up to three years total

Eligibility: US citizen or national, or permanent resident alien of US. Can apply senior year of college through just prior to beginning of 2nd year of grad school.

Deadline: Early November 

The application for this fellowship is pretty time consuming, but it's worth it! The fellowship is prestigious, and the application process can be helpful with your grad school applications. Some grad schools even require that you apply for this fellowship (although getting one is not required for admission!). 

Hertz Foundation Applied Science Fellowships

Amount: Tuition plus stipend, up to five years total

Eligibility: US citizen or national, or permanent resident alien of US. Can apply senior year of college or during grad school.

Deadline: Fall

This is a highly prestigious fellowship, but there are a lot of eligibility issues (applied sciences, tenable schools, etc.) that you need to check out on the website.

SMART Scholarship Program

Amount: Full tuition plus a stipend of $25,000 (undergraduates), $33,000 (masters), and $36,300-$41,800 (PhD)

Eligibility: US citizens

Deadline: December 1

The SMART Scholarship Program is a highly-selective, prestigious, national program that fully supports your education (including full tuition, a very generous stipend, book allowance, and a summer internship) while you are in school, and then provides guaranteed employment with the United States Department of Defense upon graduation. The program covers undergraduate and graduate degrees in a wide range of technical areas, including including all fields of engineering, physics, chemistry, biology, brain and cognitive sciences, and mathematics. There will be approximately 300 new awards for the 2012 year.

American Association of University Women Dissertation Fellowships

Amount: $20,000

Eligibility: Women who are US citizens or nationals, or permanent resident aliens of the US.

Deadline: Early November

You can only apply for funding of your final year of PhD study (hence the name dissertation fellowship). If you are a member of AAUW, you can't apply.

Ford Foundation Diversity Fellowships: Predoctoral and Disseratation

Amount: $20,000 up to three years total (predoctoral), $21,000 (dissertation)

Eligibility: US citizens.

Deadline: Early November 

Although minority status is not required, membership in an underrepresented group is considered a positive factor. 

Zonta International Amelia Earhart Fellowships

Amount: $10,000, renewable up to two years total

Eligibility: Women pursuing PhD research in fields related to aerospace.

Deadline: Early November

'Aerospace-related' science and engineering is somewhat loosely defined.

American Institute of Aeronaustics and Astronautics

Amount: $10,000, $5000

Eligibility: Have completed at least one semester of graduate study in a field related to the AIAA mission. GPA at least 3.30.

Deadline: Late January

Awards of $2000-$2500 also exist for undergrads.

Scholarships/smaller awards 

Association for Women in Science Predoctoral Awards

Amount: $1000

Eligibility: Women PhD students

Deadline: January

There are several predoctoral awards available; check the website to see which apply to you. Awards exist for both undergrads and grad students.

Leopold Schepp Foundation Scholarships

Amount: Tuition plus stipend, up to three years total

Eligibility: US citizen or national, or permanent resident alien of US. Can apply senior year of college through just prior to beginning of 2nd year of grad school.

Deadline: Early November

Awards exist for both undergrads and grad students.

Travel grants 

If you are doing some undergrad research and you want to present your work at a conference (you should!) then you should apply for a travel grant. CU provides conference funding to undergraduates through PACE. More grants may be available from the conferences themselves and from organizations like the AGU, AAS, APS, etc. Even if your advisor offers to pay it's a good idea to apply.