Astronomy

Director of undergraduate studies: Marla Geha; astronomy.yale.edu

Astronomy is a quantitative physical science that applies physics, mathematics, and statistical analysis to observing, describing, and modeling the universe. The undergraduate courses and degree programs offered by the Department of Astronomy train students in research techniques and quantitative reasoning and develop creative problem solvers. Students who complete the major continue on to top-tier graduate programs in astrophysics or related science fields, and they are sought after by employers in a range of fields from health care management to the banking and investment industry. The department offers a B.A. in Astronomy and a B.S. in Astrophysics.

Introductory Courses

Introductory courses with no prerequisitesThe department offers a variety of courses without prerequisites that provide an introduction to astronomy with particular attention to recent discoveries and theories. Courses numbered below 150 are intended for students who desire a broad, nontechnical introduction to astronomy. These courses fulfill the science distributional requirement, and some also fulfill the quantitative reasoning distributional requirement.

Courses with numbers from 150 to 199 are topical rather than survey courses. Most of these offerings fulfill both the science and the quantitative reasoning requirements. ASTR 155 is a laboratory course that provides a hands-on introduction to astronomical observing. ASTR 160 and 170 provide an introduction to frontier topics in modern astrophysics and cosmology.

Introductory courses with high school calculus and physics prerequisitesStudents who have taken calculus and physics in high school may enroll in quantitative introductory courses. ASTR 210 and ASTR 220 focus on fundamental measurements and tools used in astronomy and include an in-depth study of stellar astrophysics (ASTR 210) or galaxies and cosmology (ASTR 220). These courses overlap in content, so students should take either ASTR 210 or 220 but not both. ASTR 255 provides training in data analysis and research techniques, including computer programming and numerical and statistical analysis.

Prerequisites

B.A. degree programThe prerequisites for the B.A. degree are PHYS 170 and 171, or 180 and 181, or 200 and 201, and MATH 112 and 115.

B.S. degree programPrerequisites for the B.S. degree include an introductory physics sequence (PHYS 180 and 181, or 200 and 201, or 260 and 261); a physics laboratory sequence (PHYS 165L and 166L, or 205L and 206L); and the mathematics sequence MATH 112, 115, and either MATH 120 or ENAS 151. ASTR 155 may be substituted for one term of the physics laboratory sequence. All prerequisites should be completed by the end of the sophomore year.

Prerequisites for advanced electivesCourses numbered 300 and above are specialized and intensive. The prerequisites for these courses include ASTR 210 or 220, multivariable calculus, and two terms of introductory college physics.

Requirements of the Major

B.A. degree programThe B.A. degree program in Astronomy is designed for students who do not plan to continue in a graduate program in astronomy, but who are interested in the subject as a basis for a liberal arts education or as a physical science background to careers such as medicine, teaching, journalism, business, law, or government. It allows greater flexibility in course selection than the B.S. program because the emphasis is on breadth of knowledge rather than on specialization.

Ten courses are required beyond the prerequisites, including either ASTR 210 or 220, ASTR 255, 310, one additional Astronomy elective numbered 150 or above, and the senior requirement (ASTR 492). Two of the ten courses must be advanced courses in mathematics, such as MATH 120 or ENAS 151, or courses in mathematical methods, including statistics or computer science, such as CPSC 112, MATH 200 or above, or ASTR 356. Three electives can be drawn from any of the natural, applied, or mathematical sciences (including additional astronomy courses); at least two of these must be advanced enough to have college-level prerequisites. 

B.S. degree programThe B.S. degree program in Astrophysics is designed to provide a strong foundation in astrophysics for students interested in graduate study or a career in astronomy, physics, or a related science.

Beyond the prerequisites, twelve courses are required in astronomy, physics, and mathematics. Students complete at least six courses in astronomy, including either ASTR 210 or 220, 255, 310, 320, and a two-term senior project (ASTR 490 and 491). Students also complete three physics courses numbered 400 or above, normally PHYS 401, 402, and 439. In addition, majors choose either one additional 400-level course in physics or an astronomy elective numbered 300 or higher. In mathematics, students complete a course in differential equations selected from MATH 246, PHYS 301, or ENAS 194, and either an additional mathematics course numbered 200 or above or a course in statistics or computing such as CPSC 112, 201, or ASTR 356. 

Credit/D/FailCourses taken Credit/D/Fail may not be counted toward the requirements of either degree program. 

Senior Requirement

B.A. degree programThe senior requirement consists of a senior essay or independent research project carried out for one term in ASTR 492 under the supervision of a faculty member.

B.S. degree programThe senior requirement consists of an independent research project in astronomy carried out for two terms in ASTR 490 and 491 under the supervision of a faculty member.

Advising

Before entering the junior year, students must obtain approval of a course of study from the director of undergraduate studies (DUS).

Graduate workGraduate courses in astronomy are open to qualified undergraduates who already have a strong preparation in mathematics, physics, and astronomy. Students wishing to take a graduate course must first obtain the permission of the instructor and of the director of graduate studies.

REQUIREMENTS OF THE MAJOR

ASTRONOMY, B.A.

PrerequisitesPHYS 170, 171, or 180, 181, or 200, 201; MATH 112, 115

Number of courses10 courses beyond prereqs, incl senior req

Specific courses requiredASTR 210 or 220;ASTR 255, 310

Distribution of courses1 astronomy elective numbered 150 or above; 2 advanced math courses; 3 science electives (may include addtl astronomy courses), at least 2 with college-level prereqs

Senior requirementSenior essay or senior research project (ASTR 492)

ASTROPHYSICS, B.S.

PrerequisitesPHYS 180, 181, or 200, 201, or 260, 261; PHYS 165L, 166L, or 205L, 206L; MATH 112, 115; MATH 120 or ENAS 151

Number of courses12 courses beyond prereqs, incl senior req

Specific courses requiredASTR 210 or 220;ASTR 255, 310, 320

Distribution of courses3 courses in physics numbered 400 or above; 1 addtl upper-level course in astronomy or physics; 2 courses in math or mathematical methods, as specified

Substitution permittedASTR 155 for 1 term of physics lab prereq

Senior requirementSenior independent research project (ASTR 490 and 491)

• $80 application fee or fee waiver
• Recommendations from two teachers and one counselor
• School Report with transcript
• Standardized test results (ACT or SAT) - not required for fall 2023 admission. (See below)
• English proficiency test results - required for non-native English-speakers (See below)
• Mid-Year Report & Final Report

See additional details about these required application components below.

Please note that if your application materials include any documents that are not in English, you must provide an official English translation in addition to the original documents.

$80 application fee or fee waiver

Applicants should pay the $80 application fee via the Common Application or Coalition Application website.

Applicants using the Common Application or Coalition Application may request that the application fee be waived. Learn more on the fee waiver page. The fee waiver scale is based on family size and income in US dollars but is applicable to all international students.

Recommendations from two teachers and one counselor

Request recommendations from two teachers who have taught you in core academic subjects (e.g. English, Foreign Language, Mathematics, Science, Social Studies) who know you well, and who have seen you at your best. It is preferable, but not required, that recommendations come from teachers who have taught you during your final or next-to-final year of secondary school.

Also request a recommendation from your school’s college counselor. If your counselor does not know you well, the recommendation may still provide helpful contextual information about your school and its academic programs. If your school does not have someone serving as a college counselor, please request a recommendation from a school administrator such as a house master, principal, or academic advisor. 

School Report with transcript

Your counselor or other school official should submit a School Report with an official transcript that includes all your secondary school courses. If a question on the School Report form is not applicable to your secondary school, leave it blank. 

Recommendations and transcripts should be submitted electronically through the Common Application or Coalition Application website. If necessary, teachers and counselors may also submit their recommendations and transcripts via mail or digital upload. Recommendations may be sent before or after you submit your application; materials that arrive before your application will be kept on file. The admissions office will make reasonable allowances for late school documents in situations where it is not possible for teachers and counselors to meet the application deadlines.

Standardized test results

In response to the extraordinary circumstances associated with the pandemic, Yale has temporarily suspended its requirement that first-year and transfer applicants submit results from the ACT or SAT. The change will be in effect during the 2022-23 admissions cycles for applicants who intend to matriculate in fall 2023. 

More information on Yale’s test policies is available on the standardized testing page. Standardized tests are just one component of a student’s application and are viewed within the context of the student’s entire file. There is no minimum score required for admission, nor is there a score that will guarantee admission.

English proficiency exams

Yale requires that non-native English-speakers who have not taken at least two years of secondary education where English is the medium of instruction submit the results from any of the proficiency tests listed below.

The TOEFL requires pre-registration for available testing dates. Yale’s most competitive applicants have scores of at least 100 on the internet-based TOEFL.

The IELTS offers proficiency tests in locations around the world. Pre-registration is required. Yale’s most competitive applicants have IELTS scores of 7 or higher.

Cambridge English exams are available at testing locations around the world. Pre-registration is required. Yale’s most competitive applicants have Cambridge English scores of 185 or higher on the C1 Advanced, C2 Proficiency, or B2 First exams.

Applicants may submit the Duolingo English Test (DET), which combines an English proficiency test with a brief video interview. Duolingo’s technology and format allows applicants to complete the test at any time or place with internet access. Yale’s most competitive applicants have DET scores of at least 120.

InitialView provides live, unscripted video interviews that candidates may submit to colleges for consideration with other application materials. Interview times must be reserved in advance. There is no scoring associated with these interviews.

Mid-Year Report & Final Report

Students who do not receive new secondary school grades by February 1, including students who have already completed secondary school, are not required to submit a Mid-Year Report. This includes many international students. Applicants who receive new grades by February 1 should submit a Mid-Year Report.

Only admitted students are required to submit the Final Report, which provides final secondary school grades and examination marks. Admitted students submit the Final Report in the summer before fall matriculation.

If your secondary school provides predicted results for external exams such as A-levels, the International Baccalaureate, and other international or national testing organizations, they should be submitted by your school alongside your transcript or Mid-Year Report.

All applicants for first-year admission must submit one of the following:

• The Coalition Application with Yale-Specific Questions
• The Common Application with Yale-Specific Questions
• The QuestBridge National College Match Application

Yale will accept any one of these applications, without preference for one over another. Students should submit one—and only one—application per admissions cycle.